Summarizing the second day of holiday event
Alright, today I walked about 10 kms and hatched about 15 eggs. From what I can see, chances of finding babies are a lot more high for real: in 15 eggs I found 5 babies (Pichu, Cleffa, Smoochum, Elekid, Elekid), that's 1 baby every 3 eggs! What about you? How many of them you have?
This is what I will first hatch tomorrow http://imgur.com/a/rXNfD
Note that all incubators are from coins that I take from gyms.

Answers
On the first day my count went to 0/10 babies. Today I have hatched 11 eggs, I got 3 babies, Smoochum, Magby and Togepi.
Only have Pichu and Elekid left to complete the 7 of them, if I find them I will stop using incubators. I have bought 6 special boxes with coins from gyms too and still have 600 coins left, but I hope I don't need to use them and find Pichu and Elekid first, have 3 10k on their way to hatch (2 of them tomorrow) and 3 5k too.
Chances are higher for sure, but I am still hatching a lot of trash, really, like 3 ekans in a row, tentacools, goldeen, etc...I am not complaining, the percentage is not that bad for me 3/21 eggs are babies, tomorrow will see how it goes.