IPL no regrowth question

I used IPL for the first time tonight (the ulike air 3). I treated my upper lip and underarms. Based on the instructions, I should do another treatment on Tuesday. What happens if I don’t notice any regrowth by then? I know there will be underarm regrowth but it’s possible I won’t notice any on my upper lip. Should I do a treatment anyway? Or wait until I see more upper lip hair?