Good for you for rescuing an animal in need!
The thermostat you have should be fine as long as it says it can handle the wattage of whatever device you plug into it. A Herpstat will control the temperature to a higher degree of precision - fractions of a degree instead of swinging a few degrees up and down, but I don't think the temperature swings are that big of a deal. Some types (which I think includes Jumpstart, but if you search the forums you'll find better technical details on all the various models) will put the heating device on full blast if the thermostat fails, which is obviously dangerous for the snake if the cage gets too hot. This is a rare occurrence, but it's not unheard of.
You'll have to decide for yourself what things to buy when, but a Herpstat is a good quality piece of equipment that's worth getting at some point although that point does not have to be now. You can always keep the Jumpstart on hand, just in case. It's not bad to have a spare on hand, since it's a pretty important piece of equipment. Plus, you mentioned you might rescue another snake at some point in the future.![]()