That fertilizer will be fine. While it should be mentioned that it is not complete having only 3 nutrients, since your plants are in the ground they might get enough of the others from the soil.
There seems to be a bias against synthetically purified fertilizer on this forum. While I also use organic matter whenever reasonable or convenient to do so, I see no real need to *try* to use more organic and less synthetic. That's a subjective statement since I gradually found more sources of organic matter to compost, I don't mean to imply otherwise but if your soil hasn't been used for crops (much) it will probably be nutrient dense enough that little additional fertilizer is needed. My soil is fine after years of reuse, being amended with more organic matter for each season. Synthetic fertilizer has caused no problems, you just have to remember that's not all the plant needs.
The only way to know for sure is to have the soil analyzed. Otherwise you are watching for deficiency symptoms and playing odds based on the directions on the fertilizer package, which can work fine for most people but... having more data is a good thing.
Fertilize as often as you're willing to. Ideally you would fertilize very lightly with every watering but that can get to be a hassle. The idea is to give them small doses regularly, and as the plant gets larger and depletes the soil more further into the season, the more fertilizer it can use. When you should stop using it is when the season is over.