Depending on the species you choose to grow it is likely you will get a second, third, fourth, or even fifth fruiting with care and patience. Growing mushrooms is an art, and it takes skill to be good at it. Be patient, follow the instructions carefully, and try to maintain a humid environment for your kit and you should succeed.
In terms of yield, you can usually expect your first flush to be somewhere in the range of 1/2 of a pound to 2 lbs. This varies significantly species to species, environment to environment. It depends greatly on how much care you put into maintaining your kit! Each subsequent fruiting will likely be smaller as the fungi use up nutrients in the substrate.