As of the last bid:
Most junior A320 FO is in YYZ and was hired this summer (2005),seniority around 3000 out of 3100 or so.
Most junior EMJ Captain has about 4 years at AC (the last few Captains are guys that just got recalled from furlough)
Most junior B767 FO,in YYZ of course is around 2400 of 3100 (about 7 years seniority)
Most junior A340 FO is around 2000 (about 8 years senioriry),most junior 320 Capt about the same (9 years)
These times may improve as there are many retirements coming (100-140 per year) and new aircraft coming as well.
Why it's taking so long to call you I don't know but if you haven't got a PFO letter by now I think your O.K.Even if they called you now I think you could be in the left seat of the EMJ in about 4 years (I doubt it will go less than that as the routes are improving and the pay is good) but you could definately hold 320 FO in under 2 years.
If you get hired at 37 you will be able to retire as a widebody Captain if nothing changes for the worst (takes about 20 years).
Also dont forget that AC still plans to hire around 600 guys after you in the next 2 years.Good luck!