If you haven't planted yet then adding dolimitic lime to your soil would be better as it also provides magnesium for the plants. Vinegar is acidic and baking soda is alkaline.
If you are trying to bring up the ph of your water/nutrients before watering your plants then you would be wise to invest in a ph meter. When I add Pure Blend or most any of my additives the ph of my RO water drops to about 2.8 or less. I find adding a bubbling stone to the bucket for 24-48 hours brings the ph up naturally to at least ph 5.
I have no experince using baking soda so I can't suggest amounts to add other than to use the ph meter and add a little at a time to bring it up to what you want. I use the ph up I had left over from when I did hydro. It isn't organic but I'm not using a lot so I am not worried. I'm not looking for OMRI certification. LOL
I had to bring down my coco mix as the lab said it was 7.2 and my leachate test confirmed this reading. By keeping all water and nutrients a bit on the acidic side I managed to bring it down to 6.8 the last time I checked.
That ph meter has come in handy.