Sometimes my vision is blurry right after putting contacts in; why is that?

A few reasons maybe. Clarity of vision with contact lenses depends on a number of different factors. 1) the prescription should be correct 2) the "fit" to the cornea should be correct 3) the cornea should not be dry 4) the type of contact lens being used to name a few.... Your situation sounds more like 'dry eye' syndrome. It takes 'some time' after putting in the contacts for your vision to clear.