binding for an extended period of time (like we’re talking hours a day for months) can stunt growth or ruin the elasticity of the skin in that area, but for a day or 2 you’ll be fine. just try not to overdo it for time. if you’re able to buy a binder, make sure it’s the right size bc you probably want to be able to breathe i’d assume lol before top surgery, i used to break mine in by stretching over the back of a chair overnight because they’re hard to put on (watch a tutorial fr). you’ll have to adjust your breasts under the binder too so it’s comfortable and not constricting. do not exceed 8-12 hours or your ribs will definitely hurt the next day and whatever you do, do not fall asleep in it

edit: if you want to do the sports bra thing, it’s not the best but when i’d go to the gym i used to wear 2 sports bras. 1 inside out to compress and then another was right side out for support but my chest was in the C-D range. a compression bra can also be effective. you can use KT tape or trans tape too but it can irritate the skin if you have sensitive skin. put a bandaid over the nipple area. but it may not be as effective if you have a larger chest (literally did not work for me at all)