Ok, alternating nodes......how to explain without a picture available.....hmmm. Ok so you know how when you start a seedling and they are young to maybe a foot or so high and each node has the two leaves shooting out parallel to each other from the stem and then the two new shoots that pop from that node are parallel or equally aligned to each other.....well that happens when the seedling/young plant is still sexually immature.
Now once they have reached sexual maturity, the leaves will no longer be aligned or parallel.....instead they will be slanted or angled from the stem. Look at any mature plants you have going and you will see where that transition starts to occur and that is when the plant reached sexual maturity.
Easiest way I can think to explain to you Mac is with your flux. Think of how when you are training them and each new node pops out.....and how early on everything is nice and even in terms of each new node. Well at a certain point that symmetry gets lost and the new fan leaves and new shoots that pop out at the nodes are now staggered/angled/alternating. Hell, I will find a pic online and show you because I am not sure I am describing it correctly. Here!!
When you see your plants throwing out new nodes that look like what I circled as "alternating nodes", then your plant should be showing you its pre-flowers or getting ready to show you its pre-flowers. If they are still showing you even nodes, then you will need to be a bit more patient.
Hope that helps Mac.
. Have a productive rest of the week. 
