ON your tax forms...(if your DD 2058 was accepted mid-2018) then you will start using WA as your State-of-Legal- Residence (SLR) for all tax returns in the future until you leave military service.
In turbotax, for 2018 and on the My Info page, you will indicate that you were a resident of WA at the end of 2018, and that you "moved" from VA in mid 2018 (on the date your DD-2058 was accepted)
Then..after every scrap of the Federal Income and Deductions and credits, etc.. are filled in (Everything ! ) you start thru the state section to do the VA part-year tax return. There you will need to allocate what income you received before your "move" (yeah...you stayed in place, but for tax purposes you "moved"). All wages, interest, dividends, investment income you received before your "move" is VA-taxed income as a part-year resident.
For 2019 taxed next year...and on until you leave service (or dd-2058 again...though I don't know why you would), you'll file as a WA resident. You must not register to vote anywhere else so make sure you register there, and vote absentee in WA as you PCS elsewhere.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
