Minutes Before the Off (or start time?)

Hi, I would like to create a trigger to bet on horse racing as close to the start as possible. Just before the actual start. In the real world many races do not start at the scheduled start time but a few minutes later. If I use "Minutes Before the Off = is less than 0.2" will it place the bet just before the scheduled start time (for example for 16:45 Southwell it would be around 16:44:50) or in the period between just before the scheduled start time and the actual start of the race? I am looking for a formula that will allow me to bet even if the scheduled start time has passed but before the actual start. Have the trigger look for a bet before the actual start time of the race (even if it is after the scheduled start time).

Hi
In addition to markets minutes before the off, use Race Status conditions. for example:

markets minutes before the off is less than 0.2
AND
markets race status is at the post
or markets race status is going behind
or markets race status is under orders 

Thank you Mark. I'm going to test :-)