I ain't so lucky as having a special timer for the job. I just use an old analog GraLab and the left side of my brain
I fell in love with the Speos Stop System. Very easy to use (heck, if you can see, you can use it!) and mostly brainless. (And it allowed me to finally understand Gene Nocon's system properly.)
The stop system is based on a comparison method that allowes the printer to exclude almost all math from the equation (you do need to know how to multiply and divide by 2). It is even possible to do away with test strips and get a decent print in a few tries! Once the calibrated prints are done, you just enlarge a negative on a piece of paper with whatever exposure you like (it isn't very picky at this point, you just want to see something) and process it. Once dried, you compare it to the calibrated prints and find the one that looks the most like it. Once this is done, you identify the print you would like the new picture to be most like and count the number of prints in between both. For every print, you multiply or divide the initial exposure by 2. You print the picture with the newly calculated time and it should come pretty close to the target print.
Its only drawback is that you end up with piles of calibration prints that you need to keep (one set of 9 prints for each type of paper you have, some even push it as far as having prints for each grade also done). But on the long run, it saves a lot of time and paper
