Procedure was given to us by Boeing as we were seeing some issues with the autothrust. Company was operating about 80 737 300/400s back then and it was standard procedure. Also solved the problem and the autothrust worked fine. Still the same procedure today.
About the worst thing you could do was to push the throttles up to almost the target N1 and then push the TOGA button. That was a leftover habit from 737 200.