There's advantages and disadvantages with no-transplant.
disadvantage- Ph problems, using the same soil for veg/flower with chemical nutrients, acids are formed in the soil making is very hard to control your Ph. Unless you have a good game plan (soil, nutrients,) your gonna have problems.
Advantage- your plant roots in its final container. There's no stop -n- go. When your roots hit the side/bottom of your container they send a chemical signal back to the plant "we're out of room" the roots system slows way down. That's one if the reasons why you'll never see a 5 foot plant growing in 1/2 gallon of soil. It doesn't have the room and it know that.
You could use "cow pots" there light paper pots. The roots grow thru the pot. When you see this you plant the whole cow pot in a bigger container. The roots don't stop growing, they have new soil, and the stress on the plant is zero since your not disturbing the plant at all.
I personally use Medical Marijuana Mix soil. It lets my veg for my 8-10 weeks with only adding water. In the flower I add "Triple phosphate, and a little dried blood"
theres usually more than one way to do something. This is your first grow, so keep it simple, don't go crazy with nutrients, over watering. Yah sure your plant might not be at its full potential, but you won't have the problems new growers have. Get your toes wet in the first grow. The second grow kick it up a notch
since this us your first grow I would transplant, with the cow pots or bigger containers.
the "Grow Bible" is a must read.
and so is "intro to Plant Biology" you want to know everything about plants read the plant biology book.