yes, what you need to do is treat it like Pokeradar abuse. If you tried RNG abusing for a beldum at any point is pretty much the same. Select the Radar as the Y button on key items and start it as soon as screen comes up. Count your steps towards your patch and capture the pokemon that shows up. Pause the game and check for Nature/IVs. That will give you an idea of the frame you are right now and if you have hit your seed or not. After a few tries you can verify your seed by the patch pattern once you use the poke radar. Note that you need to read the pokeradar abuse paragraph that's on page 1 so you don't make any mistakes on frame count (capturing pokes, steps, encountering pokes, etc advance frame).
you change the date so diary comes up first and not the actual pokemart screen. Do the appropriate advances (I'd recommend something low because of this like <100) and get your poke. THEN check your seed. It's not as bad as it sounds actually, especially for someone used to hit delays in 4h gen like you. Out of say, 20 you'll probably hit your seed twice. What makes it tough is if the wondercard you are going for is not nature locked. THEN you can have some fun trying to get the right poke. Good luck
yeah they are both from in game actually (RNGed ditto and bred starter). I'm not doing any Happiness apps at all. Should I? I chose a 10 flips/ 0 additional flip seed, that means that yes, I'm doing my 10 seed verification coin flips, do I need to do an extra 10 and 0 Happiness app checks? Sorry but it's been a while and the new guide is not as thorough as the original (pre HGSS) as far as I recall.