Grass Fertilizer

Now that Summer is pretty much here, I recently started the 4-step program for fertilizing our lawn. I usually try and fertilize before rain is predicted so it won't be on the grass too long, but you know how inaccurate weathermen can be. After I fertilize I always supervise our JRT to make sure she isn't rolling or chewing on anything in the grass & I wipe her paws with a wet towel to get off any residue after she comes back in. Is there any other precautions I should take? Does anyone know how much harm fertilizer can actually cause a JRT?

Thanks for your help!