I am just learning the ropes on developing 4x5 as well. I want to make a suggestion or two based on my experience. You may want to use latex gloves (or other material) when using the tray method. Also, be sure that you know exactly where your chemicals are (maybe a little separation of the trays if you have room. I made the mistake of not having enough room and wound up attempting development in stop (for 9 minutes), needless to say nothing developed and I had yellow fingers for several days. I said several bad words when I turned the light on.......................
Novice mistakes, ain't it fun!