I hear veg starts when a plant has 4 or 5 nodes. Does that mean like right when the fourth or fifth node starts to sprout from the top, but is really small, or when the fourth or fifth node is clearly showing 5 fingers?
Mine is only 2 weeks old, but I’m trying to be prepared. 
When they are small and still considered seedlings I use Fox Farms Trio, I’ll use half strength until they get bigger, I start with the worm castings and Bat Guano first then, when they get bigger I use Grow Big witch has more nitrogen, main thing is don’t overdo it, I’m not a expert but that’s what works for me
I appreciate the info, but I was asking about growth stages rather than fertilizing.
There is no definitive answer as to when vegetation stage starts.
Answers I have seen are…
when the plant drops its cotyledons and is living solely off the roots…
when the plant has developed 3 or 4 sets of real leaves…
2 weeks from breaking ground…
If you are asking so you know when to start ferts that will depend on the medium you are in to some degree. Coco needs nutes much sooner than new soil and super soils may not need any added nutrients.
Thanks for the response. I’m totally new and asking to help me understand when veg stage starts, yes. But more specifically about the 3 or 4 leaves version. Does that mean when I can see the fourth leaf just coming out the top of the plant, or is it when the fourth leaf is big enough that I can count the number of points? I’m in soil growing autoflower indoors and I’ve already decided I will start with fertilizer at the end of the second week.
Two actual quotes…
1 - The vegetative phase, colloquially known as the “veg”, begins from the moment seedlings rise to the surface…
2 - The Vegetative Cannabis Growth Stage is the growing stage between seedling growth/cloning and the flowering stage. The seedling growth stage lasts about 2 weeks…
Point is there is no agreed upon answer…
Everyone has their own concept.
So just decide how you want to count it and stick with it.
My opinion, is that true vegitative growth begins when the seedling has branching. Once they are actively rooted and growing laterally as well as vertically, that signifies the change to the vegitative state.
Although, yes @Spiney_norman is correct saying vegitative is the moment the seed breaks the soil.
Really, there is a point in the beginning growth phase where the plant is putting on material exponentially. That in my mind is the vegitative stage.
Some plants do this right from the 2nd or third node! Others are stretchy and dont branch actively for a while.
I just copied that post from a grow site.
Just showing how many opinions there are about this.
Thanks for all the info ya’ll. I was really just trying to figure out what was considered a node, but all of this info is welcome and appreciated. I gave little Bud but his first small dose of nutes this morning at day 17 above ground and I can already see growth since this morning.