For me personally, around 450-500mg of codeine or 300-360 DHC does the trick! An empty stomach, in solution, a cigarette ten minutes after ingesting and then a joint maybe twenty minutes later again, just to set it off. Get comfy and listen to some classical music. Can't beat it for a quite night!
I'm fortunate enough to have access to 30/500 co codamol as well as dihydrocodeine in 30, 60 & 120mg pills.
When I first started taking these, however, 90-120mg codeine and 60mg DHC was spot on.
One thing I don't hear many people comment on in these forums is feeling more active and focused. I used to take these at work (followed by a cigarette, never a joint!) and found if I was busy then my performance was noticeably enhanced. It was great, because as soon as it was break time and I had a seat, I felt warm and fuzzy and totally at rest.
One piece of advice I'd give to someone new to codeine/dihydrocodeine is that the buzz can be very subtle, and rather than instantly increasing dosage to "feel more", learn to appreciate the high and how to optimise it, i.e. empty stomach vs. food after ingesting, crushing and adding to water for faster absorption vs. swallowing whole for a smoother, gentler but more sustained high etc.
Be safe and enjoy yourselves! ;D