Thanks chinkenfish4, a couple of questions if I may:

1. it looks like when you jump up and eat the mushroom you let go of the A button, and then at some point afterward press A again to jump while maintaining p-speed, all while keeping B down throughout. I can't seem to find the exact instant for that second A press, is there some cue in Mario's growing animation you look for? I've succeeded in doing that maybe twice out of a hundred times, I just can't figure it out.
2. I've also tried to jump over the koopa at the beginning, only succeeded in doing it once without landing on the block above it, now I've basically given up on that and just kick the shell to get rid of the hammer bro. I know it should only be a light tap on A, from the looks of it you also let go of B for a split second? I might add that I'm playing on OpenEmu (Nestopia core) on a Mac using a PS4 controller (wired, not over bluetooth), could there be timing issues in emulation that differ from original equipment for these precision button presses?

EDIT: I'm dumb, just notice you're also using emulation. How do you get the input display in there? I've always wondered what software to use. And is that an 8bitdo controller?

Hello, I hope I'm not asking any dumb speedrunning noob questions that shouldn't belong in this forum. I've just seriously begun about a month ago to practice maintaining p-speed in any% no wrong warp, since my previous best was 13:25 without maintaining p-speed and getting pulled down by the first hand in world 8, and I want to try to get my time down to at least sub-13. My current strat is to get the mushroom in the bouncy block in 1-3, but I can't figure out how to consistently maintain p-speed after getting the mushroom, every time I do manage to maintain speed it's always by accident, and I can't seem to find any tutorials on when exactly to push A (I'm assuming it requires a precise time to tap A afterward, like maintaining speed after exiting pipes and doors, which I can't figure out either); if anyone can offer some pointers or point me to a tutorial, I'd be very grateful. Also, from watching mitchflowerpower's runs, I can't figure out how it's possible to not crouch on the white block at the end of 1-3 and still get behind the scenery, and I can't seem to find any info on how it's done either. Would anyone be kind enough to offer some pointers on this as well?