Harris will probably get a convention bounce that will revert to her baseline by Labor Day.
In recent cycles the convention bounce has been pretty muted.
National polling error at this point is fairly close to what it is right before election day. State polling error is still fairly high at this point. So we could expect the most movement there between now and November.
Harris has been in a bit of a honeymoon period. But so has Trump- his approval rating did shoot up a bit after the assassination attempt and RNC. So September will probably give us the best look at the true state of the race.