I use my base soil on the property, and ammend and add mulch -- To do this, I lower the bed and path area and put the soil into the raised bed box. For example, with 2 ft wide paths and 4 ft wide beds ( my house) I lower the soil about 6-8 inches ( as my raised beds are 12 inches deep), shovel that over to a pile, level the spot, put the raised bed there, check its level and adjust if needed. My raised beds are 4 ft x 12 ft. This gets much faster when doing multiple raised beds, so that after the first ( empty) bed is placed, then the second spot is dug down and leveled by throwing that soil into this first bed, and continue on until the last bed is filled by that soil pile from teh first beds site.
Why do this ? Well, maybe what you can buy is different than here, but from what I have seen when friends have bought in soil ( or compost for that matter) this soil is not realy very good, it is fluffed up with alot of organic matter that gets eaten by the worms, microbes, etc, and soon their soil level is nothing. ANd, if that is what you want, do it on site, it will be cheaper ! If you don tknow your soil composition, do a jar test, look it up , soil in jar with water, shake to mix well, let it settle, first part in sand, put a piece of tape ( I forget the timing, look it up) then leave the jar for a day or two to see then the layers. You can als do a test with test strips on fertility, the NPK and Ph, to see what you may want to add. What I find is that sandy or clay, what it needs is organic matter the most, and that means after adding nutrients, rock dust powder, etc... into the soil, you are going to want to mulch very thickly, maybe with alfalfa hay, go buy a bale or two. Put it on 6 inches deep, and this first year, just transplant, do not direct seed, let the worms eat the mulch and make your soil better. That bought soil isnt good anyways, might as well do your own
This first year, leave a bit more room between plants, and go for chard and kale and not broccoli, fr example. So, plant greens, a few tomato plants, zuchini -- you will get plenty of yield, as greens and zuchini dont need alot of nutrients and you can out stuff directly into the tomatoe holes when transplant or maybe you are going to amend soil before planting(with organic or regular plant food, I like the recomended soil ammendments from How to Grow More Vegetables Than You can Imagine.... your bed is nominally 1/2 of a 100sq ft bed recomendations, so easy to figure out what to add -- they have a base recomendation for first year, if you dont test, my bok is upstairs, maybe I will look it up for you later if you want it), while you build up soil.