While studies have shown that children raised bilingual do take a little longer to start talking than those raised in monolingual households, this delay is temporary and certainly not a general rule. Alot of us grew up in bilingual households and grew up to be fluent in both. My view is that you proceed with raising baby with both languages. Being able to speak Filipino will help him identify with his roots -- especially when he visits the Philippines in the future.
I have read an article about myths about raising a bilingual child. According to studies, confusion on the part of the child and having speech delays are all myths. In fact, it is encouraged that you expose the child to both languages if you want him to learn the 2 languages at the same time. http://www.babycenter.com/0_raising-a-bilingual-child-the-top-five-myths_10340869.bc
English first because this will be the means of your communication if you will be migrating in US. Don't worry because once your son is ready you can slowly teach him our native language. Also from time to time to can show to your son Filipino culture and the beautiful places that we have. Always pray..
I think that it is best to learn English first since that's his tool to socialize with the kids in your neighborhood. If you think that your child can speak English more fluently, then you can inject Filipino by teaching him filipino songs, etc.
My husband and i agreed that he will speak to the kids in english while i speak to them in tagalog. Like you, we don't want them growing up not knowing how to speak tagalog. So far, it is working with my kids.