Question: at which occasion, do i make the modifi...

thats up to you, i can tell you how i do it. Beginning of the week, end of the week updates with some pictures, telling the days on the pictures in the dairy. update stuff like humidity temperature pH. and thats basically it. I count day 1 from the first day of veg. that's usually 1 week from germination (when the stem becomes rigged) The more the better usually and if you go into detail it will help a lot if you have any questions at any time. Whatever you do, have fun while doing it, and if someone can learn something from looking at your dairy, its even better. Happy growing and welcome

Potatoe, potatoes.

up to you. I count weeks as they finish, not leading into them. So Vege week 1 is once they've been above ground for 7 days - or at least the first wave of sprouts are roughly 7 days old and some will be younger. Germination/sprouting isn't too exciting, so adding in frist week above ground helps round it out. but you can do it any which way you want that makes sense to you. The diaries are something you'll look back on and consistency of that stuff helps compare apples to apples.

I put all germination related stuff and then after seven days since it sprouted thenI start week two of veg. But at the end of the day your diary your rules. You do it how you see fit.

You could put everything germination related (germination method etc) in the germination week and depending on the germination method, once the seed breaks the surface of the soil or you transplant the germinated seed into a growing medium and see the first cotyledon leaves you could start counting veg days.