For a small cube with less than 1m records, should not take more than couple of hours, or say one day. Then another day to do final tweaking. Again, totally depends on what you want to build and how big is your cube / query results are.
Rakesh please tell me if my cubes have 1.5 crore records can i break it on the basis of years. i have 3 years data and what is the query for that (how can i use where clause) also when i am trying to pick the data from cubes after 2,39,000 it halt and not allow me to pick the data after that i have tried this 3 times but same results.