We're in the same situation. We speak English and French at home and DS's daycare is French and Spanish with only a very small about of English. I also chose it for other reasons. I'm all for it and don't care one bit if it causes any kind of delay. Everything I've read says that they catch up by 2.5 or 3, if they are delayed at all. The only challenge we've encountered so far is that it takes me longer to figure out what his new words are. I find I'm mostly listening for English (even though I also speak French, my brain's default is English) and it takes me by surprise when I realize that he's been using a French word for weeks and I just thought he was babbling! The Spanish is even harder because I don't know very much. He sometimes get frustrated when he's trying to tell me something and I don't understand it but I think that's normal for any toddler no matter how many languages they are learning.
Happy mumma to my boys Henny Tom (Nov 30, 2008), Arlo Odie (Oct 5, 2010), and baby SISTER! due mid-Dec 2014.