In Progress
I started a lot of the hyacinths later this year than usual, October and November rather than September, but it did not seem to delay flowering at all. I had a reasonable number of hyacinth flowers on Christmas Day or shortly thereafter.
As always I try to update the spreadsheet 1. when I start the bulbs, 2. when I take them out of the dark, 3. when they're in bloom, unfortunately though, there are lots of gaps and I've had to average with the 80 percent or so data I have. I also gave away a lot of the hyacinths as gifts so couldn't see their final performance.
The average time the bulbs stayed in the dark was 10 weeks. I go by how they are growing rather than the elapsed time and take them out when they look ready, when the bulge of the flower is out of the bulb. That time was as little as 5 weeks this forcing season or as long as 17 weeks (the end of January). I just took the last vases out of the dark then even though they didn't look ready but they all bloomed.
Then after they came out of the dark, they bloomed on average 3 weeks later.
Peter Nyssen Anne Marie only 8 weeks in the dark, blooming 3 weeks later. I find the pink hyacinths are the earliest. As far as I understand Anne Marie and Ann Mary are the same variety.
Peter Nyssen Blue Jacket longer in the dark, 10-12 weeks, blooming 4 weeks later
Peter Nyssen Blue Star variable from 9-13 weeks in the dark, blooming 2 or 3 weeks later
Peter Nyssen Delft Blue quite variable, some as little as 6 weeks, some as long as 13 weeks in the dark then blooming 3½ weeks later
Peter Nyssen Pacific Ocean on average 8 weeks in the dark but some as little as 5 weeks, some as long as 13 weeks, blooming 3 or 4 weeks later
Peter Nyssen Pink Elephant on average 11 weeks in the dark, blooming on average 2½ weeks later
Peter Nyssen Splendid Cornelia 9 weeks in the dark, blooming 2 or 3 weeks later
Bloms Ann Mary 10 weeks in the dark, blooming 2 or 3 weeks later. Not as early as the PN Anne Marie.
Bloms Caribbean Dream 10 weeks in the dark, blooming 2 or 3 weeks later
Bloms Delft Blue 13 weeks in the dark, blooming 2 or 3 weeks later
Bloms Miss Saigon on average 8 weeks in the dark, blooming 3 weeks later