Well I am by no means an expert but I can tell you what my experience has been thus far (about 15 5x7 negs). I actually use brush development by inspection but the process is pretty much the same. You simply follow your normal development procedure in trays (or I have heard of some using tanks with hangers). Then at about 75% of your normal dev time you pull the negative out of the tray and have a look. You'll need a 7 or 15 watt lamp with a green filter. I use an old Kodak brownie lamp with a green filter. I got it at my local camera shop for about 50 cents used. Now when you look at the negative you'll see your highlights developed against a milky white base. Now I've found that the the highlights should stand out fairly good from the milky white shadows, but not too much. If you can really really tell that it is black then you've probably developed too long, whereas if the transistion from milky white to black is too gradual, then you probably need to go a bit longer. I start looking at about 6 minutes when I'm using Rodinal 1:50...3 minutes when using ABC Pyro. You'll have to develop a few times to get a feel of exactly what the highlights should look like, but it doesn't take long at all. After about the 2nd or 3rd time you'll have a good idea of what you're looking for. You can find another explanation of this at micheal smith's site: http://www.michaelandpaula.com/mp/index.html . It's under the 'writings' section. Hope this helps.