At the end of the previous year you journaled “closing stock” (P&L) to “stock” (balance sheet). Going the other way this year you would journal “stock” to “opening stock”, then at year end do “closing stock” to “stock” again. Opening, closing and general purchases then appear as three separate lines under “cost of sales” on your P&L, and the overall cost of sales for the year is opening plus purchases minus closing.
Personally I would leave the stock on balance sheet for now so you get a reasonably accurate running cost of sales, and put in the opening and closing stock journals at the same time next time you do a stock take.