Am I too old to attempt going pro in tennis?

I know asking this altogether is probably ridiculous since I'm old (to go pro anyway). But, I'm 22 I have about 9 years of playing (and training) behind me, with a couple 2 year breaks in between. Honestly, I'm at a level 4 (very rusty) but have incredible coordination and ability to improve quickly, especially with a good coach. Is is too late to go pro? How long would it take?