Sorry, I can't help with knowing when to prune, but I am curious how big your tree is and what size pot you have it in.
I've had one potted for about 2 years now, but it only gets a few lemons each year.
Also interesting about the blooms. Mine has bloomed in spring so far.

I'd wait until late winter to do any pruning. That seems to be the general consensus I could find.

Our in-ground Meyer Lemon was blooming at the end of November, so this must not be too uncommon.

Ty