When you get your results, you can get a rough estimate of the time to most recent common ancestor with your matches from the "block tree" view. They show you how many SNP mutations are between you and the common ancestor. A commonly used number is an average of 83 years per mutation, but there is a lot of variance around this and disagreement about how reasonable it is. But going with that, you see an SNP mutation every 2-4 generations on a family line, so if you count your SNPS back to your common ancestor with a match, multiply by about 3 and that will tell you roughly about how many generations back the ancestor is.
If you are looking at STR matches (which can be a different set of matches than your closest SNP matches -- it is for me), then you can use the "Tip" feature next to the match name and it will tell you estimated probabilities for the number of generations back to the common ancestor. AFAIK, this is considered about as rough as the estimates for SNPs, i.e., pretty rough.
I don't know of an online guide, although I'd be interested in seeing one. There are very knowledgable people in the private Facebook group on Big-Y, YSEQ, etc. (very complicated group name). Then there was a separate group that split off over some kerfuffle about which I know little. That other group has knowledgable people too. And a lot of the haplogroup project leaders know a lot --- you can join several, since you will belong to multiple haplogroups at different levels of the phylogenetic tree.
