How would you calculate this? Re Periods TTC

[MyNansACheeseGrater]

My last period started 8th of August at around 8-10 am in the morning

What I’m wondering is (and I know this is a vv daft question lol) would I be cycle day 30 or 31 if that makes sense

Please no judgment thank you

Today is day 30, 1st day of bleed is cycle day 1

@ThreeLittleDots Thank you!