You need to be testing daily with a reliable drops kit for ammonia and nitrite and doing an extra 50% change anytime you see either show up. In addition to this a 50% change with siphon is needed. Cycling will take up to 2 months. You will see an ammonia spike first, then nitrite. Ammonia should fall and stay at 0 first, then nitrite, leaving you with only nitrates after a full week. At this point a weekly 25% with siphon should be enough.
Make sure the heater is next to the filter so the heat circulates and you don't end up with hot/cold spots.
How are you monitoring temps?
Since he is new, how did you acclimate him to the new water?
What conditioner are you using?
Can you share new photos?