How did you teach your kids to speak English words (at least )? How old were they when you started having English sessions with them?

Use English in all your conversations and activities like story/craft time. If you are also allowing your child to watch TV shows or videos, choose the ones in English.

We started talking to our son in English ever since his birth. We just talk to him as is. Now, his primary language is English and can understand Filipino well too.

Speak to them in that language, and patiently correct their grammar mistakes. That's the best way to teach anyone a language.