Can you use a loop when you first get your nose pierced?

The best person to answer this would be the hopefully professional piercer who would be doing the job.

A less professional answer: depends on the type of loop. A captive bead ring, common in most professional studiOS is a likely option when you get your nose pierced, whether it is a left or right nostril piercing, or a septum piercing, If you did not go with a CBR when you first had the hole poked in your nose, you will have to wait until the piercing fully heals before changing to something else. The type of loop that is basically a barbell with screw on end caps, bent into up to 300 degrees of arc should also work. I have something similar in 4 gauge through my right nipple with no problems.

If you are talking about the type of closed loop commonly sold in jewelry stores and meant for ears, i would recommend against it, especially if you are getting an amateur or DIY piercing. Those things are EVIL on fresh piercings as they provide lots of places for gunk to build up, increasing risk of infection.

Whether you go professional or half assed with it though, i do suggest NOT going with any sort of loop for a nise piercing at first, start with something low key that employers or potential employers are less likely to notice until it heals, then go with the CBR or whatever after it is healed fully, this makes it more likely that you can avoid the hassles of being forced to pull the steel out of a not healed yet piercing, which invites scarring, infection, bleeding, and the hole healing closed.

http://www.bmezine.com/ is likely to be your best source of info online, though beware, it is not particularly safe for work, or around parents if you are under 18.