Don't It can be a waist of time and very frustrating .
First you have not said what you want to make, decide on how accurate of a cockpit you want to make. Make a budget and start saving for your build. Seriously best thing i ever did was to put money away every month just for the cockpit build. When i found a military trainer i made an offer and the guy took it I had the cash and the deal was done.
I would suggest if you don't have access to a museum with a display. Find the most accurate model produced make sure you know any faults with it before purchasing it. The modeling sites are full of information. Use it as a cockpit in side and out reference. get a good set of calipers for measuring.
Get a cockpit lay out do your research ,IFF Control Panel C-6280A (P), Oxygen regulator panels and a few others are used in multiple aircraft and can be found on eBay. get the panel Miil spec. Making your console to hold real control panel allows you to use real ones if you find them.
This is the best way to start a build in my experience.