Hi
Your first question is difficult to answer because it depends on your laying system. The laypro 88 is a staking plan that could be applied to any selection at any point before or after the off. However, the market's lay book percentage is likely to be at best value just before the off, whereas in-play the liquidity will be much less and consequently you may not get matched at a "value" price, or might not be matched at all. Hope that makes sense.
There is a constant at the top of the trigger file you can change for when to place the bet. It's mins_before_off and is set to 1 in the default trigger. If you want the trigger to fire 10 seconds before the off set it to 0.16