I was offered a position in an area that interested me. It was below my career level but I was offered it with a very specific justification, which also made sense. We had a long discussion with the employer, during which I expressed that I was looking for a more advanced role.
We settled that I would accept the more junior role with worse conditions that those I was seeking, but "if everything goes fine" get promoted very quickly, within the first months. This was expressed explicitly during the discussion. There's nothing about it in my contract, since you don't mention such things in contracts in my country.
I've now started. I have the impression my manager thinks I will spend years on the current grade. Why do I think so? My manager encourages me to "experiment" with tasks and not feel pressured. Also, I don't think the projects which I'm about to take over offer me the opportunity to show what I can - my function will be more junior than what I did before.
What is the right time and way to approach the topic of promotion? I don't want to come over as delusional, given I've just started, but I accepted the position believing it was temporary and a way for me to show what I can and I'm stressed that it doesn't look like it.