What is the best time of year to start a vegetable garden?

Typically spring, but there are many veggies that can be planted throughout the growing season. There are also fall crops. What zone are you in? This will determine the best success for your planting. What do you want to grow?

the best time of the year depends on your last average frost date. wait 1 week after that to plant. if you start your veggies in the house under lights- start them 6 weeks before the last average frost date. there are winter veggies that can take a nip of cold and be fine. plant what you like to eat.

That depends on your location and if you want to start them from seed or established plants

What growing zone are you located in?

https://garden.org/nga/zipzone/

If you are starting from nothing, work on it this fall so it will be ready to plant in the spring. Oh, so many variables, though. What kind of soil do you have? Do you need to amend it? Can you just plow it up? Do you need raised beds? (We went to raised beds because we can get massive rains that leave lakes on our flat lot. Takes more watering but at least it doesn't all rot or wash away!) Maybe you should start at the library with a borrowed book on vegetable gardening.