Wait! Say that again?
If you cast on with the long tail method, then you have cast on AND knit your first row in one smooth move.
Why does this matter?
Well, it depends what your pattern calls for you to do on your first row. If you are knitting a piece in stockinette stitch, then your “first”, non-cast on row will be a purl row because you knit a row while casting on.
The easiest way to check where you are in the pattern after a long tail cast-on is to see if the designer has you starting on a RS (right side) or WS (wrong side).
After a long tail cast-on, you are ready to knit the WS.