Is that 80 days from seeds or transplant? I grew them here in NY from seed, indoors, & then transplanted small plants that were about 3/16" diameter but I think even then it took longer than a couple months from transplant. I've never directly seeded onions in the garden. I also planted them from a large company's plants around the end of April and had onions before the end of July.

The important thing is to get them well established before the summer solstice while avoiding really cold temps at the same time. Each leaf the plant has grown should equal a ring on the bulb, (though a bit harder to count on Cippolini types without cutting them equatorially.) Days get shorter after the solstice; I think this may be the time of most bulbing, triggered by the solstice. Maximum hours of daylight here at my lattitude is 15hrs 21min from June 17th thru June 23rd. Yours should be longer if you are further North. BTW, exactly 14 hours of daylight begins on April 28th here in Buffalo.

I usually grew Borettana Cippolini.

matermark~ it's 80 days from seed. I'm going to do exactly what you did & start them indoors and transplant out near the end of April as well. I wasn't planning on growing onions but I got the seeds and thought I'd give 'em a try. They sound delicious!!
If anything, I've learned about day length & it's effect on onion development. Who knew!!??
So you figure bulbing is achieved most after summer solstice when day length begins to diminish. I'll try pulling some just before and leaving some beyond the summer solstice just to see what the difference will be.
June 20-21 are longest here with 15h41min.
14 hours daylight starts April 25 here
Thanks for your insight and here's wishing you a good onion harvest!!