Listen to the GM with 292 balls (uncomfortable) and me, not the random with 3.
You are in division IV, it is easy to promote, I did it in my first season and didn't lose a single match for the entire season even though I had no idea what I was doing and didn't have 1/100 of the mentoring available to you.
I have a level 6 trainer and I can 100% understand you wanting a level 5 as soon as possible, but trust me, they are a bit overrated. The difference between level 4 and 5 is around 5% at most, so after 20 pops you would be one better off. Just managing minutes so he gets 48+ every week and does single position training is much more important.
Obviously we all have different aims but I won division IV in my first season and then won division III in my second. Whatever you decide to do you must not neglect your arena and the rest of your team.