A side note not prop-specific, but may be interesting to folks ... I now order my B12 (Cyanocobalamin) from Maximus - VERY reasonable price compared to what I was paying. I also get B-complex 100 injection (Maximus offers B-complex 100- the one you want).
Chip is right about therapeutic benefits - I do 2ml (1,000iu/ml) B12 w/HCG (not mixed,separate) and 1ml B-complex day after test injections + 1-2ml B12 halfway between test injections (day 3).
Great for energy and all other B-vitamin benefits including liver health. Common treatment for chronic fatigue (debate out there on whether it works - does for me and many I know, which is all I care about

. I believe MoparMuscle says it can help with HCG absorption which is why I time it this way now. Hell, I hear it's great for hangovers.
If you've never had a B12 injection, 1-2ml/week the first few months will wake you up as if you've been sleeping for years... not the same for everyone, but my wife, parents and many friends all describe it the same way. After a while, you just feel better and won't get that wake up feeling but you'll miss it after a couple weeks.
As an FYI, Common doses I've seen are 3K iu 1-2x/week. At one point I was prescribed 10,000iu B12 2x/week plus 1ml B-complex 100. Took for 6-months - compounding pharmacy said 10K iu was fairly common (not so common was 2x/week). My wife still does 10K iu 2x/week, me I didn't feel any difference between what I do now and that so I prefer to take what works and no more. I definitely miss it if I go a week or two w/out.
Subq or IM? Depends. My wife like subq, I like IM. Subq takes longer to to absorb/work, IM faster. If my wife needs a boost, 1ml IM is the way she prefers - seems more 'instant' (I agree). Seems docs are split 50/50 on what they recommend (docs we've used over the years anyway).
B12 is in and out fairly quickly - subq is slower than IM. Try both.
Not medical advice, just personal experience since I and my family (going back to my grandparents) have a lot of experience with B injections. Personally, I wouldn't go more than 2,000-3,000iu/week to start.
OK, back to prop thread...