oh okay, so the nature/ability/shininess are determined when he gets the egg and the IVs are determined when you pick it up like in 4th gen
The thing I'm worried about is the fact that I don't have a way to trade the egg between different games/save files to get it to hatch shiny, as I don't have the means to transfer my save from my actual gba game to the computer and I'm pretty sure that you can't extract individual .pkm files from gba .savs like you can in gen 4. Other than sending someone both the savs who has the means to trade between them (such as you, lol) is there any way to do it?
btw I'm about to go somewhere so I may not reply back until tomorrow, thanks again for your help.