Do the problems that are at or above your level, and you can probably do it in 2 weeks of you spend 2 hours every night and 8 hours total on weekends. If you figure in 2 minutes per question, and 5 minutes on each one you get wrong, you should be able to figure out a rough estimate of how long it'll take.
I did the hard 1/3 of OG11 RC, CR, PS, and DS, plus the entire OG11 SC, and that took me about 1.5 weeks of the above description of work. The easy questions are too easy to be of any use, so I wouldn't waste time on them if your level is way above that.