Smallmight

I am planning on enlisting as an aerospace medical technician. I have been wanting to get Lasik for awhile now (29 years old) and based on what I've read, my refractive errors fall outside of the acceptable range (-4.75, -1.75 and -3.5, -1.75). Is it best to get surgery prior to going through MEPS (I'm not on a tight timeline) or go through MEPS, confirm that I'll need eye surgery if I want to continue and then get it done 6 months prior to enlistment/basic? Thanks!