It took me exactly one day to start Monquista and to finish Valencia. So, you start Monquista around level 13 and should be 15 by the time you reach Cool Ranch. Plus, doing a few side quests wouldn't hurt.
It really depends, if you have finished all the side quests or not. It usually only takes a couple hours, if that to complete Valencia. You get there at level 16 and leave at 17 or 18, if you have done all side quests that is. If not, you could only be level 14 to 15, then good luck!
For quests i think 2 hours would be fine for both main and side quests, if you go to farm Phule's equipment depend on your luck ^^ (personally i did Valencia in 2 hours and then 4 hours for Phule, still to have to find what i need , aka the medallion).