I think a good rule of thumb is that if you can fly a full circuit around the field inverted in the trainer you are ready to try your second model. So yes, your trainer should fly inverted. Just carry it a little higher bc in a trainer it can be hard to do an outside loop to pull out of inverted flight so you have to roll it over.

Grant, a good thing to do now is to start build a second plane. Something like a Sig 4* or equivalent. Take your time building it and learn some more building skills. Take your time with the trainer, only when you have "mastered" it are your ready to move on. I totaled my second plane bc I lacked the skills to fly it, I went back and spent months on my trainer and then I was ready to move on again.