I'd wait for the 5000 series, it shouldn't be long now. Right now is literally the worst possible time to buy PC and the discounts on the 3XXX series aren't very good considering what is coming.
Another thing you could do is buy the cheapest Ryzen CPU you can possibly find right now, and then buy the 5000 series when it's available - that way you get a working PC immediately, and you will only be out a few bucks after you sell the old CPU. With a B550/X570 board you're good to go with both.
This is a better board than that MSI B550, it's cheaper and you get the X570 chipset:
https://www.memoryexpress.com/Products/MX77774
Also, MSI's subsidiary company was caught scalping their own 3XXX series video cards on eBay, so fuck them.
If you're only out to save money, Ryzen 3000 will be even cheaper yet after the 5000 SKUs hit the shelves as well.