Tell do you recharge your iphone to 100 percent before using it?

Or 97-98 percent

If I need to use my phone, I don't wait for it to be fully charged. If I don't need it, I allow it to fully charge.

It's up to you. It has no effect on the battery's life expectancy.

I make sure the battery is fully charged before I go anywhere with it where I might not be able to charge it. Otherwise I charge it when it gets below half full or so, depending on what I'm doing.

I normally charge to 100%. Sometimes less if I have to (say if I was going out but the phone hadn't finished charging) but I try to avoid it.

Should allow the phone to drop below 20% once per month before charging to keep the percentage of battery use correct. Other than that, charge it when it's below 50% or you need to use it a lot that day.

I plug mine in overnight, so its always a 100% when charged