Would agree with several others that 2019 class is not done by a long shot. It's true that for many P5 schools (especially SEC and ACC) they have many commitments but that's not true of others (ie Big Ten), and definitely not true of other D1s, with a few exceptions.
Interestingly, my 2019 son was invited to two camps of very attractive D1 schools that said they were still looking for the last one or two 2018 pitchers.
For 2020s and beyond, please watch these discussions and be on top of the process. Still, the best advice I've been given is that the "timeline" varies and don't panic because you make bad choices when you panic.