If you're specifically targeting your first 100 customers, I would make the free trial much longer. At this very early stage, you're better off with customers using your product than with paying customers. Look for customers 101- and beyond to be paying your bills. So do a 3-month free trial instead - or longer. I would also target customers in the same industry and possibly in the same geographical area. You're more likely to get referrals if you have a universe of users that are similar.