How many days per month are acceptable to be late to work?

One will usually get you a warning and two will have you looking for employment elsewhere. A business does not operate for the employees convenience. If you are late someone else has to work over causing the employer to have to pay overtime. If you want the job and a good recommendation when you find a better job later on, be there when you are supposed to be there. It's really not that hard to be on time.