The bomb has 4 possible locations. Spawning in the first basement loses 1-2 seconds in backtracking. Spawning on the 2nd or 3rd floor of the far right building can cost 5 seconds in backtracking.

It's a slightly shorter walk/backtrack to get the yard of psychos from the right level door instead of the left side at the beginning. You can get a fast speed Tiny (runs away) to open the left door for you, but you still have to wait for the psychos to come in to range if you wait at the door. Waiting is unreliable when you're already resetting constantly for bomb position.