My son is now 22 yrs old but he still acts as a teen. It's been a long struggle since he turned 15. How long does it take before boys become mature?

I just learned last week that he's looking for an appartment (I think that he actually found one) and wants to move with a friend of his who is a drop out who just started a new job at $12/hour. My son works between 1 and 3 days a week in a bakery at less then $10/hour. The appartments he's looking at are $650 + heating + electricity + ....in bad neibourghoods (he does not see that).

How can I convince him (if it's not to late) that he should first find a good job, get a driver's licence and save his money before moving? Even his girlfriend backed out and no longer wants to move with him (she's still in College) and it did not change his mind.