I think any answer to this would be highly opinionated. There are very loose definitions of what's considered "beginner", "intermediate", and "advanced" in terms of both programming and in skill.
In terms of programming, I would rate them as such (again. There's no clear-cut definition so it's only my definition):
Beginner - Linear progress meaning you can add same amount of weight every workout and/or week. Very general. Very basic. Designed to build strength while also giving the athlete a chance to learn the basics. Probably not a lot of accessory work unless the athlete needs something to rehab them in to proper lifting form. See Stronglifts 5x5 or Starting Strength
Intermediate - Non linear progress meaning you may not be able to add weight every week. Variable rep/set scheme to put more emphasis on recovery. Maybe a few accessory lifts to fill out training gaps that the main lifts don't cover. Also added accessory lifts to increase volume without a dramatic increase in fatigue. See 5/3/1, Texas Method or Candito 6 Week Program
Advanced - Non linear progress. Highly variable rep/set/intensity scheme. Usually focused on improving a single lift. Often times these can be peaking programs for meets, and add such will completely overload the CNS by the end of it. That means very high volume and very high intensity which increases risk of injury for people not ready for it. See Sheiko or Smolov.
I don't think there's a set, strict point at which someone is considered "beginner", "intermediate", or "advanced". 1200 seems like a strange cutoff as I would consider that advanced or even elite for a man competing in the 116KG category but intermediate for someone competing at 264kg. Dots or WILKS might be better suited for that, but to answer more generally, you should move on when:
You're no longer advancing in your current program. If you're current program is leaving you exhausted (and it's not peaking), then you may need to consider moving to something more variable to emphasis recovery. If you're not exhausted but not making progress, then you may need something with more volume and/or intensity.
Your bored. This goes for any program really. If you don't enjoy it, then you won't perform it to its full potential. Move to something you find more interesting.
Side note: don't follow celebrities when trying to decide what to do. They're usually focused on different goals then you (usually aesthetics over strength and athletic ability). They also lie about their training and drug use because the celebrity trainer they pay too much money for makes them sign an NDA to protect their "training secrets".