OPOL ... except I still want to speak both!

I speak Chinese and English, my partner speaks English only. We live in an English-speaking country. I understand that this means I should prioritise Chinese at home, since bub will learn English virtually everywhere else he goes. However, I do still want to be able to speak English (it's my main language), and obviously any communication with my partner will be in English.

I'm wondering how much English I can get away with speaking in a day without hindering bub learning Chinese?

He is nearly 7 months old.