I just updated my G1/dream to CyanogenMod-126.96.36.199 with danger spl. The actual flashing of the 3 different roms (danger-spl, defanged base, cm-188.8.131.52) part only took about 20 minutes. This was after I had already downloaded all of the necessary files, copied them to the SD card and verified my radio version (Settings->About phone->Baseband version).
The first time you root your phone it will take a bit longer than this. One of the reasons it is much faster after the first time, is because during the initial rooting process, you load a "recovery utility" that you will use later.
Now to wait for CyanogenMod-5.0.7 to drop.