I've seen a number of people mention just slowly dumping it into the skimmer basket, as well.
I don't know if it is safe to do both together or not, but it wouldn't be a bad idea to do them separately, since the borax will also slightly raise your TA, and you don't want to overshoot by adding the baking soda at the same time without accounting for that rise in TA.
with that info, I should do borax, let the pool turn over, then check TA and add baking soda??
That's what I would recommend, but I am also fairly new to this, so you may want to confirm with someone more senior than I.
These two chemicals can be added at the same time as they are not going to react with each other. However, I would recommend adding the borax first by broadcasting over the pool while the pump is running. Then check your pH AND TA after an hour. Brushing the whole pool is a good idea too after adding powdered products. Borax will raise TA slightly but mostly affect pH. Then determine if you need to add baking soda.
Yes do the borax first. Don't pour it into the skimmer though. Once it has cycled retest and go from there.