Yes, do it on the purl row. Usually, just this one row difference won't show in the finished garment.

Moni

Did you cast off the first few stitches for the armhole yet?. I don't know whether you've finished the left or right side

Here's what I'd do--Imagine you are knitting a pullover. To decrease for the armholes you'd cast off 3 or however many stitches it calls for on the knit row and knit across.

On the purl row you'd cast off the same number of stitches on the other side. Then you'd decrease on both ends on the next and every alternate row by k1, knit 2 together on the first side and s1,k1 PSSO k1 on the other side.

I hope this helps you visualize what you have to do

The V neck starts the same row as the underarm shaping so I'm only doing one side of the front at a time, on 1/4 of the stitches that were cast on for knitting the body of the vest in the round. Then I'm going to be adding yarn to do the other side.

This is the last time I'm going to make up my own pattern!

I'm trying to visualize what you've done. Did you cast off for the underarm and then for the neck then purl back and continue on that side?
Are you going to knit a neckband afterward? If you are and if you've done it this way, then the solution is simple. Join at the neck edge and knit--this is just a continuation of the knit row you started for the other side. Do your neck decreases on this row and the underarm decreases on the next purl row. Then continue decreases on both ends on the knit rows as you did for the other side.

If you ever do do your own pattern again you have to have a plan. For instance-- If you had looked at any other pattern that has a V neck and proceeded to follow the way it was done --the method not the stitches-- you would know how to proceed now. Don't let it throw you for a loop. There is a solution to every problem you just have to find it

If that is indeed the way you did the other side and you are incorporating the neck band, then you can join on the armhole edge. Remember this row is just a continuation of your first row on the other side. So if you are decreasing more than 1 stitch for armhole then do it on this purl row. (If not then do your decreases on the next knit row.)Then decrease for the neck and armhole on the next knit row. This will make the neck decreases one row off the other side which is nothing and will be all right.

Thanks, that helps me visualize it. The patten that I used as a starting point was garter stitch, knit in 4 identical pieces, and sewn together. I kept the deep V style, but used a lace pattern in the round, up to the armhole/neckline decrease row. Now I'm doing stockinette stitch, knitting back and forth. I think I'm okay - I'll let you know when it's done.