02 deville Fuel gauge question

So i recently bought this car, and noticed that the fuel gauge is screwy. I searched on here for the answers, and I found that it's a fairly common issue with the car, as well as what it is, and how to fix it. That's great, and I'll do that, but in the meantime, I wonder if there is anything I can trust. In other words, even though it still shows full, and says that I have 530 mile range, will the low fuel light come on at some point? If i keep the gallons used screen up, is that going to be accurate? Short of just topping off my tank every day, what can I do until I can get it fixed?