How long, seconds and distance, does it take for a horse to reach "cruising speed" from a standing start?

Question

Some jurisdictions use race times based on flying start, some standing start and I am trying to reconcile them.

May vary with distance I realize but for now interested in sprints.

Answer 1

Got some info elsewhere: one person used 1.8 secs, apparently Nick Mordin suggests 1.7 secs.

Hope this is of use to someone else.