I apologize ahead of time, I'm pretty sure this question has been asked in some form, but unfortunatly something is wrong with my brain and I dont seem to follow the same train of thought as others

Im not sure how to word and search for this. Ive tried but no luck finding anything helpful.
Basically I've decided to do my CP first. I have the wood and buttons. I have a friend lined up to cut the wood and make the holes for the buttons. I have the buttons and wiring and Ipac and can do that part, and in the mean time im working on finding someone to do an overlay for me.
My question is, when this is being done in 3 different steps, how do I do each step so that it's correctly done and lined up for the next step...
By that I mean, can I just judge on my own the size of the CP I want? I dont have my Cabinet yet (waiting on auction next month) so basically if I wing it on the size to what I think is big enough, will it fit on most cabinets? ( Im thinking about a mid sized cabinet. nothing 4player, nothing small. itll be a 2p setup.) or is there a standard or preferred size when it comes to CP's?
then, assuming I get that worked out. Do I judge the placement of the buttons on my own as well? Just stand in front of it with a friend, and see where it feels right? Theres really no standard or "normal" way of doing this?
Then... assuming those two steps are done, and Im getting a CPO made. How do I measure out where my buttons will be, so they can line up the artwork appropriately.
Thanks for any help, and again, Sorry if this has been asked before.