I checked Deepstate for the rate of advance in Donetsk and it's about the same as last year with the important caveat that zero large settlements have been taken this year.
If they're lucky they'll have taken 80% of Donetsk by Christmas. It does seem bizarre that they think they can take all of Donetsk oblast by the beginning of September. I wonder where that reasoning comes from.

They better get a move on and sharpish, only fifty days left.