Date of Rank is based off commissioning date (those commissioned during the may/june timeframe will have a DOR that coincides with the Naval Academy regardless of actual commissioning date).
AFADBD is based off the day you get commissioned. ie, no money till then unless you work PTAD with your OSO.
As mentioned earlier, if you do PLC, your PEBD is based off the first day of OCS provided you do not accept any tuition assistance for school. This can be a pretty good deal, especially if you do the split juniors/seniors program, your PEBD will be the first day of Juniors. Because of this, you can potentially be maxed out on the pay charts for quite a while.
It seems like the TBS wait has progressively gotten worse over the last few years. Im sure it is related to downsizing. When I went through, I waited about 4 months from commissioning (though I heard I was lucky) to class up. They were doing 7 officer companies a year with around 300 Lts in each. They packed us into Obannon like sardines. Do they still do that many?