Which decrease to use for neckline

Help! I’m knitting my first sweater for a baby. It has a collar that I add later and the pattern for the neck shaping states the following:

Working both sides at same time with separate balls of yarn, decrease 1 st at each neck edge every other row 3 times – 13 (15, 17) sts each side.

Then later in the pattern I have to pick up the neck to add the collar:

With right side facing and smaller circular needle, join yarn at right shoulder and pick up and k23 sts across Back neck, 10 (12, 14) sts down left front neck edge, 17 sts from Front neck stitch holder and 10 (12, 14) sts up right neck edge – 60 (64, 68) sts.

I’ve managed to get to the point where I’m working two balls of yarn around the neck and think I understand that but what I can’t figure out is whether given the downstream instructions whether the decrease at the sides of the neck should be a bind off, k2tog, ???

Any help is greatly appreciated! Full pattern with picture is here:

Welcome!
Really sweet pattern. I like a k2tog or ssk at the neck in this case. You can work either but if you do a k2tog on the left shoulder (as you would wear the sweater) and a ssk on the right shoulder, the lines of decreases follow the neck edge. It’s nice to work these decreases one stitch in from the edge but that’s also a matter of personal preference.

Thanks for this! Do you think that method will work with the additional collar here? Will the lines of decreases be visible? Thanks!

If you put the decreases at the very edge, they’ll be hidden when you pick up sts for the collar. Even if the decreases are one stitch in, the collar will very likely roll over and cover them.