I'll add some of my old observations from when I did soil grows. I used to move 2 gallon veg plants into 5 gallons right as I flipped. I figured the plants would need lots of fresh nutrients to get through flower. After two grows I yanked the plants and noticed the roots had barely moved into the new soil, often the old 2 gallon rootballs would just pull out of the 5 gallon container. Following grows I would just topdress and maybe add some liquid feeds into the 2 gallon containers and in the end, I didn't notice one bit of difference between the two methods.
Your always gonna get bombarded with information as a new grower, just do what you feel is correct. Don't be fearful of failure. There is always information that is gained from it. Always stay focused on what you do, what you observe, what you learn, what advice is given and then what the results are. Then take all that and make adjustments in future endeavors.