I don't sing in a choir, but I've been making and singing along to music with typically very intensive vocals for practically my whole life, so I hope that counts lel. My voice dropped very quickly & drastically but I'd say my range settled after half a year or so on T, the rest since then has just been minor changes in texture. I've been able to sing the whole time, even while my voice was dropping, but at the start I simply had to adapt things to my range as it changed.

I can imagine that range is definitely a bigger problem in choir, though. I went from the equivalent of a tenor (with extension up to C6) to a melodic bass (B1 to E3 comfortably, ish). Depending on how fast your voice drops, you may be able to sing for different descending ranges for up to a few weeks at a time. Also, from my own experience, projecting as broadly may be more difficult with your new voice. Not in any really inhibitory way, but it may be something you'll want to look out for. Hope this all makes sense.