1809 isn't even fully available yet (3-29-2019). Now I was able to get it to pop on my stations configured with zero days of delay in the Semi-Annual channel, and I just did all 8 stations here at home.
But here's the weird part... my wife's laptop is 10 Home, and it WOULD NOT pull the update. I had to feed it a USB key with 1809 on it and run setup.exe to force it. It completed, and all seems well so far.
The only snag I've found in my testing with 1809 in the field is I had one unit, fresh install of 1809, and when a user with redirected folders logged in, the event log blew chunks with permission errors. I had to rename the profile directory he was living in, log in a second time, it made new folders, then I had to copy all his files down to the workstation and put them back from the workstation side. Simply plopping the files into the correct folders on the server didn't work.
So it seems to me that 1809 is back to the same stupid redirected folder bugs that 1511 shipped with. yuck.
Semi-Annual shouldn't get 1903 until October or so, and if you're worried about that just use a GPO to set your delay to six months. I'm adjusting all of my policies to get 1809 out before the end of May, and then hold again for six months. I'll see 1903 in Oct / September at best. But I'm always working my stuff one version behind. Been that way since 1709.