When should I think about database sharding?

hey everyone im hitting a point where our main user database is getting pretty large and im starting to think about performance implications were seeing longer query times especially during peak hours ive been reading up on database sharding as a way to scale but it seems like a pretty complex undertaking with potential downsides like increased operational overhead and challenges with cross-shard queries whats your experience with sharding at what point did you decide it was necessary for your applications and what were the biggest hurdles you faced