About 2 or 3 months ago I had been hired by a software firm as an intern. Upon talking with HR around that time, they told me that they would start paying me once clients started coming in (it's a startup firm), which would be around April. It is now April, we have been receiving clients, and I want to ask my boss for a pay stub, so I can plan accordingly and apply for student loans if necessary to finish my degree.
Whats the most polite way I can approach my boss about this matter?