it is no problem to do seed stitch form the first row. Just do it.
you CAN knit or purl one entire row. Some knitters like that for a fancier showing of the cast on edge.
But if the pattern says seed stitch form the beginning: just k1 p1 till the end, then do the next row making a knit where a purl appears and the other way around (as normal in seed stitch).
You may be a beginner but you got it just right: that is what the pattern wants at the same time there would be options. I vote for the starting without a base row.