Hi, new here. I'll throw my 2 cents in for what it's worth. I try to time my warm up to be as close to the start of the race as possible. Still leave yourself enough time to get to the start so that you can put yourself in pack where you need to be. I like to be warmed up as much as possible before a short race (5k-10K) so that I'm ready for those first fast miles. I throw in strides as I'm doing my 10 minute warm up.