lol, no secrets, really. The only abandon one that I got was my black, now adult dragon, Icis. All of the other ones I got at the 'hour' mark- most I got though I do think were from glitches, because I would get on at like 12:47 for example, a random time, and there would be 'mystery eggs', and I would ust grab them. Just every time I see that one has hatched, I go and wait for some eggs and grab a new one quick.
But yes, abandon eggs do count- but hatchlings dont. Or so it seems for me anyway- cause I've only been doing this for less than a week myself. lol.
So for those of you witrh hatchlings and less than four eggs- wait and go for it! Get somethjing cool!lol.
Good luck!