Need some help on post-completion OPT 20 hr/week rule

Hi everyone,

I just to explain my situation before I ask my questions:

I graduated May 2025 and am currently on my post-completion OPT. I started a volunteer opportunity to stop my unemployment clock while I continue my job search. For volunteering, I have to sign-up for shifts ahead of time. There aren't too many shifts available, but so far I have been able to get around 21-22 hours of volunteering in each week. The problem is, my supervisor emailed me last minute that one of the shifts I signed up for tomorrow has been cancelled, which means that right now I'm looking at only 17 hours of volunteering this week.

So my questions are:

1. Will that take days off from my unemployment days? If so, how many?

2. What do I do during holidays? For example, we are closed on Thanksgiving so I know that the week of Thanksgiving I may not be able to meet the 20 hr/week requirement.

3. Can I make up hours? Like let's say I volunteer 17 hours this week, and next week I volunteer 23 to average 20 hours/week.

Of course I'll talk to my supervisor tomorrow and see if there are other opportunities available this week but I just wanted to get some insight beforehand.

tyia