Personally I would not buy fish that had just arrived at a lfs. You don't know how far they have travelled, and what conditions they travelled in or for how long. They have then been dropped into a new tank with different water conditions then you come along and stress them further by having them netted again, transported yet again and then dropped into new tank conditions. Leopard corys are not that robust. I think it would be kinder on them if you waited and at least made sure the danios survive the cycling first.
Corys shouldn't be added to a new tank. Let it mature a bit.