Yes! I've got it!!!!!!!!!!! I've finally found out how to know which dragon or egg you'll get just by looking at the breeding time!
First, go to https://dragon-story.wikia.com/wiki/Eggs. There you'll see a table format. Under Incub. Time, you'll see the hatching times listed below. This is the same as the breeding times! So, for eg, if you breed a red dragon and a red dragon (breeding time: 10 secs) you KNOW you've got a red dragon. Cool, huh???