Filling Fell Out During Cleaning, Dentist Can't Replace for 2 Weeks?

I had to recently get a new dentist, because of insurance reasons. I was 3 months overdue for a cleaning, so I started getting anxious about my dental health (due to already poor dental habits and history).

During the cleaning, one of my fillings popped off. I understand a cleaning wouldn't be the sole cause of it; it must have been failing already. The soonest they could get me scheduled to replace it was two weeks later. The filling was on the top of my furthest back right molar, so now there is just a hole there, and the only thing they told me was that it might be sensitive to cold.

Is two weeks not a risky length of time to be without a replaced filling? Other than a saltwater gargle and eating on the other side of my mouth (info I gathered from online), should I pick up dentemp for now? And does using temp filling make it difficult for the dentist to do the actual filling?