While trying to get an All-Stars PB, I decided to mess around a bit and try out BBG (everyone was telling me it would softlock/crash the game) and i managed to do a weird BBG/FPG/whatever you want to call it. Could this be a potential time save?

That loses time as you still have to walk to the castle to have the timer start counting down.

Edit: To add more information, the reason this happens is because the backwards pole glitch is activated in 8-2 on the Japanese version of the game. When Mario grabs the pole during "bbg", he instantly snaps to the other side of the pole, but he isn't high enough to land on top of the flagpole block, just like regular bbg. As a result, he's ejected to the left of the right side of the pole, which happens to be inside the flagpole block. The rest of the end level cutscene plays out as usual where Mario walks to the right until he reaches a solid block, which in this case is the castle.

Full flagpole glitch crashes on both versions, but you aren't doing a full flagpole glitch here thanks to the backwards pole glitch.