Make a non updating time

Okay so, my problem is fairly simple but I don't know how to do it, I'm fairly new to excel. I need to set cell A1 the time when cell B1 stops being 0 (cell B2 tracks how many attemps there have been of answring a question), and when B2 is 0, I don't want there to be anything, and I don't want it to update. If someone knows how to do this without a macro, I would appreciate it, even though it seems impossible. But it can also be done with a button, so B2 would be unnecessary because it would be manually stated that there has been someone that tried.
Tl;dr I need to set a cell value to a specific time that doesn't update (with a press o a buton or when a value changes)