Thanks for the responses!

I will try to keep the water as warm as possible till the heater gets here. I ordered the Hydro 25 watt submersible aquarium heater - it had good reviews so I hope it works well.

Luckily I work from home for the next few weeks so I'll be able to monitor the temp.

When can I expect him to start eating?

Also, the pet store just got a new shipment of teeny tiny ADFs and I'd like to get at least one buddy for this frog (once the tank is the right temp) - is there any issue about putting a much smaller ADF in the same aquarium?