I'm not an expert, but I would suggest the same.
My reference for this is Prof. Akşit's statement about the TF-6000: "Our TF-6000 engine has already achieved 3800 lbf of thrust. It is even capable of being used in its current state during an emergency." This means that engines like the TF-6000 can quickly reach two-thirds of their targeted thrust level and can even be used in this state in an emergency.
If this can happen with the TF-6000 engine, why not with the TF35000 engine?
Ah, i don't know from where to start to explain, let's start.
First of all, TF 6000 engine was designed and developed from start to be a 6k lbf engine but it took years of work before it could even run reliably at 3,800 lbf. The big chunk of time wasn't about getting the last 2,000 lbf; it was about getting the core architecture right in the first place.
TF6000 Engine Simplified Timeline:
2017: Project Start
2023: Critical Design Review (CDR)
2024/2025: First Prototype
2025+: Testing Begins
202X: Mass Production?
And this is an engine that is not AB capable, that will be the TF10K which we heard nothing of, do i have to say how many extra years will it take for it to finish?
Same story with the TF35000. Saying "we'll use it at 2/3 power(23K lbf) for the first planes" sounds good, and it's probably the plan. But that doesn't magically shave years off the schedule. You still have to go through the entire, long process of designing, building, and testing the core just to get it to that stable 23,000 lbf state.
So yeah, the idea is right, but the clock doesn't reset. The core R&D is the fixed timeline, whether you're targeting full power or a partial one. You still gotta build the whole house before you can decide to only furnish the ground floor.
Where this approach really saves us is if we hit a wall with materials. If we can't yet make the turbine blades and composites that can handle the full stress and heat of 35,000 lbf, we can still fly. We just dial back the power and use the engine at a thrust level our current materials can handle. It gets the jet in the air while we continue to develop the tougher parts for the full-power version.
TLDR;
The engine wont be ready before at least 2035, if TEI makes the unimaginable, at the best case scenario we will see matured TF3X00 engine not before 2032-2033.