So supposedly we should’ve been entering the last week of filming but I’ve heard rumblings that there’s actually 3 weeks left of filming so let's see when they actually wrap up. That massive New Asgard set for example still looks very much in use and undergoing significant modifications as well.
Filming schedule:
Thor Ragnarok : July 4th to October 28th (3 months and 3 weeks)
Thor: Love & Thunder : January 26 to June ? (4 months and 3 weeks ? *)
* Plus 1 week in NY.
Spectulating about the movie running time for TLT i put all the Thor films plus the 2nd Guardians since they're making an appearance, also Civil War since they've said TLT has an avengers feel almost and that's a pretty apt comparison and of course all the Avengers films.
Thor ----------------------- 1 hour and 55 minutes
Thor: TDW --------------- 1 hour and 52 minutes
Thor: Ragnarok -------- 2 hours and 10 minutes
GOTG 2 -------------------- 2 hours and 16 minutes
Avengers: AOU --------- 2 hours and 21 minutes
Avengers ------------------- 2 hours and 23 minutes
Captain America: CW - 2 hours and 27 minutes
Avengers: IW -------------- 2 hours and 29 minutes
Avengers: EG ------------- 3 hours and 1 minute
Now taking into account that TLT will have filmed for a considerably longer period than Ragnarok, it's almost safe to say that it will be longer as well. I'll go ahead and say TLT will slot around the 2h and 20min mark.