How long can you leave a puppy in a play pen?

I just bought a 12 week old teacup chihuahua -- I return to school in a few days, where i'll be going from 8 to 3 monday thru friday, but have every intention of spending nights and afternoons with him. My mom will be home regularly and I have people who would be glad to stop by everyday and see him...is it okay for him to stay in a pen with pretty frequent interaction throughout the day? Because the rest of the day I am playing with him and holding him.

If you have regular visitors, it should be fine. I'm assuming that the visitors will be doing potty breaks. Besides socialization, potty training is crucial at this age.

Don worry it will be just fine but make sure u toilet train him. u don like to see poop and urine in the play pen

Thats fine. You can also put a small crate with soft bedding in the pen so the pup has a safe, quiet place to go.

Puppies really shouldn't be left more that a couple of hours at a time and when fully grown no longer than 4 hours. You need to start of slow leaving just a few minutes and then slowly build it up.