If you apply for more than one job and you would like job A the most but job B says they'll hire you before you hear about job A, is it ok to tell job B that you need to give them a week or so before you accept the job because you're waiting for another company to get back to you?

I applied for too many jobs at once and I'm trying to find the best one, assuming they'll hire me, and I don't know how this works.