Just knit every row to start, then when you go to start the stockinette st, decide which side of it looks better to you and call it the RS. The rows on the other side will be the purl rows for the WS of stockinette. When you finish (is that what you mean) just knit a WS row instead to start your 10 rows of garter st and BO when you've done them. If you're off one row it won't be that noticeable.
sue- knitting heretic