At least 8 out of every 10 Christians have heard, read or listened to messages pertaining to this very topic.
Meaning of Wilderness Experience
Have I been in the wilderness? The answer is definitely Yes. I believe every genuinely saved Christian would have their own story to tell concerning their experience in the wilderness. Any Christian who hasn't been there should question the genuineness of their salvation.
When I say 'wilderness' am not referring to a physical dry and arid land but a spiritual place of preparation. We're familiar with the story of John the Baptist living in the wilderness and feeding on locust and honey. But he didn't spend his lifetime in there. The wilderness was his place of preparation. When the LORD was done equipping him He launched him forth into Israel to fulfil his ministry.
Luke 1:80 KJV
And the child grew, and waxed strong in spirit, and was in the deserts till the day of his shewing unto Israel.
We're also familiar with the story concerning Jesus being sent into the wilderness by the Holy Spirit immediately after John the Baptist got Him baptised in River Jordan. There He fasted for forty days and nights after which He was tempted by the devil.
Matthew 4:1-2 KJV
Then was Jesus led up of the Spirit into the wilderness to be tempted of the devil.  And when he had fasted forty days and forty nights, he was afterward an hungred.
Today, we are not sent to a physical wilderness like John the Baptist and our LORD Jesus Christ were, but a spiritual one. But there we are also taken through almost the same process like they were.
Why The Wilderness?
By now you should start asking "why was it always the wilderness first before their ministry?" The shortest answer is simply because it's indispensable to our impact and success in ministry. If Jesus Christ who is fully God and man needed it, how much more we who are mere mortals?
God calls us to an intimate relationship with Him first before launching us into ministry. There is a lot to learn in the wilderness (including knowing His voice).
When God calls us, we can admit that we are always nothing close to being ready to carryout the assignment He entrusts to us. At times it's scary. We can't even imagine ourselves preaching and doing all that He says we will be doing in our ministry.
When we are called we are often unqualified for the assignment. The wilderness is where God equips and qualifies His Saints for the ministry He entrusts to them.
What Happens In The Wilderness
A lot. The wilderness is a place of uncountable tests, trials and temptations. Remember this line... "then Jesus was led up by the Spirit into the wilderness to be tempted of the devil"..
The Father allowed such for His Son and the Son did not object because they both knew it was necessary.
In the wilderness God puts us through a pruning process. This process is necessary to cut off every part of our life which is not Christ-like so that we can bear more fruits and have scandal-free lives and ministries in future.
John 15:1-2 KJV
I am the true vine, and my Father is the husbandman.  Every branch in me that beareth not fruit he taketh away: and every branch that beareth fruit, he purgeth it, that it may bring forth more fruit.
In the wilderness God works on us through His Holy Spirit in us to strip off everything that is not of Him in us (including Self and Flesh).
In the wilderness our pride and independence is broken. It's in this place that we learn to depend only on God. He may take away every other thing we relied on for sustenance(if necessary), leaving just us and Him.
For some of us who are rebellious like I was, in the wilderness we learn obedience. Even the Son learnt obedience through what He suffered:
Hebrews 5:8 KJV
Though he were a Son, yet learned he obedience by the things which he suffered;
Our faith will get tested and built in the wilderness. I can remember God letting me go through things that were hard to believe I'll scale through. Then He lends a helping hand when my faith was almost gone. What that always did was strengthening my faith in a double portion.
In the wilderness there are diverse attacks from the enemy, it can be so annoying! God allows this so that we get our spiritual muscles strengthened, learn to depend on Him and learn to give Him all the glory when He gives us victory.
It is where God works on our Character: That dross of ungodly Character gets scraped off in the wilderness so that we have the Character of Christ.
How Long In The Wilderness?
It may be you are currently experiencing some of the things I've said here so far. It may be you are in your wilderness. So the question you feel like asking now is how long will this last?
The Flesh and Self don't just hear God's voice at once stay clear, they struggle to stay in the way. That brings us unnecessary suffering and possibly elongates the length of time we spend in the wilderness.
If we choose not to let go of Self, Flesh, Sin or whatever God wants us to get rid of while in the wilderness, we will spend more time in there! We don't want that I believe.
The most important things the LORD expects of us in the wilderness are OBEDIENCE and COOPERATION. When we obey and cooperate with Him, we give the Holy Spirit the right of way to work on us without our resistance. That in turn limits the time we spend in the wilderness.
Another factor which determines the length of time we spend in the wilderness is the nature of our calling and ministry. A greater Assignment may possibly mean more time in the wilderness. Our crosses come in different sizes. Don't rush the process! Just let God have His way.
If this message is for you, know that whatever you're currently going through is just part of the process. Hold on to the LORD because He took you in there, He'll also send you out. We don't determine when we are ready, He does. And when we're ready He'll communicate to us in a way that we know we are, without a shadow of doubt.
1 Peter 5:10 KJV
But the God of all grace, who hath called us unto his eternal glory by Christ Jesus, after that ye have suffered a while, make you perfect, stablish, strengthen, settle you.