For activities I do senior year, do I list the hours I intend to do or the hours I have done?
So on CommonApp (not super familiar with the other versions but it is very likely this advice carries over) you list the weeks that you participate in said activity, the years active and the hours/week. In that sense you put the weeks that you will be doing on average throughout your history of doing that activity or to be safe just input the number of weeks in a school year (I think it’s 36). As for hours per week if your activity ramps up over winter break you should do the average time you will do that year.
You should not list what you have already done and not what you will do unless I’m fairly obscure circumstances. The only one I can think of is either the activity ended or you believe now is more impressive than latter but that’s super rare to my knowledge.
Hope this helps and please comment if you need clarification as I’d be happy to help clarify!
I would say the hours you have done.
They already know that you just started your senior year and haven't had the chance to do much.