You could be looking at four weeks or so. You can cycle with the fish but it will require daily water changes, monitoring of the water and will take at least as long as the shrimp method.
I would say the first thing you need is your own testing kit. API master freshwater kit has everything you'll need.
Keep in mind the store wants to sell you stuff without regard to what is right and/or proper. They managed to sell you damsels which i dont' even know if you wanted or not, they are some nasty fish.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.