first, let me say good on ya for deciding to kick, and good luck. you're in for a hell of a ride. although, the subs should make it pretty manageable. i'd seriously consider taking off of work though. that's about the worst place in the world to wd.
i'd go ahead and take your first sub dose once you start feeling sick. if you're starting to feel sick, you should be clear of PWD. that's been my experience at least. (i've taken them too soon, too, and it fucking blows like no other.) once the eyes start watering, the skin starts crawling, and the legs start kicking, go ahead and dose 2 mg.
personally, i wouldn't ever dose more than 2 mg. the weird thing about subs is that less is more. i'd prefer 2 mg insufflated over 8 mg oral any day. i'm sure you've heard this a million times though if you're a fellow phile. i'd try and go something like 2, 2, 2, 1, 1, .5, .25, .25. you want to get off of the subs as quickly as possible. due to the extremely long half life, wd from subs can be worse than the wd from the fun stuff as it just drags onnnn and onnnn and onnnn.
honestly, if you've never kicked before, i'd almost just recommend going cold turkey with the aid of a shit load of xanax. basically just comatose yourself for two days and you'll probably be straight. i don't know your history, but my first kick was relatively short. each time after that was longer and longer it seems. idk.
at any rate, good luck, bro. just remember, there's light at the end of the tunnel. i too had an injury that had me on pain meds for a long time and ended up getting hooked, so i know what you're going through.
feel free to pm me at any time if need be.