Apologies lol I guess it's steriotypical to say "he" on here when you're unsure...even being a female myself! There are people on here who swear by those cheap rheostats, but you really have to have extremely consistent temps in your house/room in order to make it work, and not many people are usually willing to take the chance of a temp spike since they aren't very reliable like most thermostats. I guess it's safer to keep the rheostat at a lower temp, but once you get a reliable thermostat it will take some trial and error to figure out what to set it at. Given my room temps and different fluctuations, mine are set at around 100-102 in order to achieve 92 inside the enclosure with a temp gun. But when I lived up north, and I lived in an old drafty house in the winter, I had to keep mine as high as 108 in order to get the same temperature.
As long as it doesn't drop below 75 I wouldn't worry.