https://sws-extension.org/

That just inserts a 2 bar offset for the count-in.
Code:
reaper.SNM_SetIntConfigVar( "projmeasoffs", -2) -- offset measures


also if you don't want it to insert the 2 bar offset you can comment that line out with --
Code:
--reaper.SNM_SetIntConfigVar( "projmeasoffs", -2) -- offset measures