In all honesty, it doesn't matter. Just keep doing jobs until you get a special quest. Save before you talk to Delvin or Vex about new jobs and make sure they give you a job in a different city than one in which you've already done the special quest. Reload otherwise. You can also reload if Delvin and Vex give you the same city, and that way you don't accidentally do 6 when you only needed to do 5. In other words, there's not much of a benefit to keeping track.
You will be notified immediately the next time you talk to Delvin that there's a special quest in the city, so it's not like you have to wait several game days doing unnecessary quests.
(Side note: If you had the PC, you could try
help TGTQ01 0 through
help TGTQ04 and see if there are any variables counting the quests you've done toward them. I'll leave that as an exercise to the reader since it doesn't apply to the OP.)