p90x arms routine

p90x routine……………..?
just wondering if you have to follow the p90x workout cds in a specific order or can you just mix and match and do whichever cd you feel like doing (note that i’m still planning on following ALL the cds, i just want to know if i have to do it all in order from cd 1) for example instead of doing chest and back on day 1….can i do shoulders and arms?
of course you can, my gym instructor said, if anything you do constant that would be great..
Day 3, P90X Pre & Post-Workout