Drug info - studying/focusing

[Stationary Traveller]

Hello everyone,
SWIM has a friend who he can get some Ritalin off of (not too many though). As finals approach and swim has reached the pinnacle of lethargy through very frequent use of marijuana he needs something to keep him focused and absorb a lotta information. SWIM will simply use it to study better and actually be able to understand what he reads and not give up immediately after starting.

Now what SWIM DOES NOT need is you to tell him to deal with college work without drugs or whatever, it's simply not the solution for SWIM for other reasons.

What I'm asking is the dosage info. He has access to (very limited amounts of) 10mg Ritalin pills. How much should he take for his mind to get focused (he doesn't want euphoria or whatever doesn't care about the "positive" effects, as long as he can sit down and finish his work and get up)? Obviously SWIM understands everybody is different etc. etc. but what do you find useful?

Also, how long after would it take effect? Should SWIM just take the pill and start studying immediately? SWIM will be using it orally he does not want to experiment or anything with it. He has heard many stories of people using it as a study aid, and wants to strictly stick to that as he isn't a stimulant type of person.

Thanks in advance