I am assuming that your existing hair is currently about 1/2" long, but if possible you might want to try to go a little longer on your first full cap. The shorter you go the more perfect the unit has to be in terms of ventilation, knots, cut, base size and shape, etc. 3/4" or even 1" would give you a little more room for error.

Dino does a great job getting his units to work below 1/2" at the sides and back, but he's been doing it forever so he has all of the kinks worked out, plus he does his own cut-ins. He has been around lately so hopefully he will stop in to give you some specific pointers on a super short style.