I've been bidding with a site called Key to Choice for well over a year. My mother helps me bid for 3 flats a week in Edinburgh. When I asked them over a year ago, how long I'd have to wait, they said I should get a flat in the fall of this year.
They only counts the bids though once you're moved onto 'silver priority.' So any prior bids you stacked up, even bids that took up years and years of your time, aren't even counted.
I was told I've been bidding for 13 months, and I may wait 14 to 18 months.