Sorry, but the next MSQ update (5.1) won't be until around 22nd October 2019.

This is based what we saw with previous expansions and 4.1 came out 16 weeks after 4.0 was released. With Heavensward, 3.1 came out 20 weeks after 3.0, but SE said at the time that they were extending the time before the the patch to give their staff time off or something like that.

So yeh although we don't know for sure, end of October is a fairly safe bet.