I think around March / April we will only see the 16 core 32 thread parts which I also think will require 550/570 motherboards, I think it will June / July when AMD start bringing the R7 12/24's, R5's and R3's out, they already confirmed we wont see they APU's until at least Q3 2019.......and the reason I think June or July for the others is, dont forget, they are built from the silicon with faulty cores that they switch off which didnt meet the R9 standards, therefore take a bit longer to sort out (bin) and build.
We saw the same thing with the 1st edition Zen's, first we got 1800X, 1700X and 1700, all 8 core 16 thread parts, 2 or 3 months later we started getting R5's and R3.
My initial intentions were to just get a 6 core 12 thread part on 1st edition, but when they didnt come out at initial release, the itch got too much and I decided to go for an R7 1700X instead, the day I went to order one, it was out of stock, sold like hot cakes, so grabbed a 1700 instead, glad I did in the end, it overclocked just as wel as a 1700X and even to 1800X speeds near enough.
CPU, Cooler and DDR4 RAM then sat on my desk gathering dust for nearly a month in the battle to get an AM4 board to stick it all in, there was a major shortage of boards back then.