Honestly I ride easy for 20 min, do a few spin ups in the next 5 min and then I'm normally good to go.

For the run I'll run about a mile, then over the next half mile I'll do 3 or 4 strides then I'm normally good.

For the swim I'll do a 10X100 set on 15 to 20 sec rest, normally start slow and as I feel better I get quicker. I'll then know I'm ready for my workout.

Edit: It's obvious that I don't know what pre-workout is.