Agree, totally have to work from the edge back to the final position. Can't plow a ditch then cut the fin at the edge, that's asking for tear out.
Your way is marginally more stable, but my way is marginally more accurate.
Although, as I think about it, accuracy is not really needed here. Still, either way. I think it's good practice
Geo, I forgot to mention in PM. I told you via PM you need a deeper rabbet to compensate for the carpet thickness. If the bare rabbetted wood is flush with the floor with installed, then it will be 1/8" too high when the top is carpeted. If you wrap the carpet around, then it's another 1/8" proud.
I just remembered for your rabbet width (you said 0.75" and 1.00"), you need to widen that too to compensate for carpet if you upholster the backside (and you should!), or else it'll be a super-tight fit.