Sorry for the late response, but Chanel keeps the pieces from old seasons until they sell out. I went to the boutique last month and saw some pieces from 24C, which released in November of 2024. They might be sent to other stores, but you can arrange to pay for an item online and have it shipped to your home (I think this requires purchase history in stores? Ask the SA if it comes up)
As for when they sell out? That depends on how many pieces of that particular item were made, how popular they are... It's impossible for us mere shoppers to tell.
I would act soon as possible, because they don't make more of these seasonal pieces once they're sold out, and this seems like it'd fly off the shelves (pink, mini bag, top handle, all things Chanel enthusiasts love)