Lots of NPs have children and still carry a full load. Whether you're working 4 tens or 5 eights, or any derivative therein, it won't make a difference on what your work-load ends up being. Regardless, you're putting the cart before the horse. Get through school, learn your craft, then worry about your schedule down the road. Kids will happen regardless of your schedule and you may not easily find someone very flexible (if ever). That's the reality of this business. Unless you are in independent practice, you are at the behest of whomever your employer is and their goals.