I suppose the timing depends on if you have one of the anemic iphone ones or a full 2.4+ amp USB charger. Given that charging status is unreliable at low charges and charge tends to "come back" a bit when not actively drawn.

My current phone has an old battery and can go directly from 40% to 70% charge in one refresh cycle (10-30 secs?) after plugging in to my ikea charger.