At this age, everything you as a parent or caregiver say in the presence of your young child will be recorded somewhere in the baby's brain. Their brain capacity is very sharp and ready to save information, despite the fact they don't vocalise it back until when they turn 2 or 3 years old. But once they start speaking, the bilingual brain can act in a unique way, sometimes delaying the speech, or not.
It's our role as parents, to continue the exercise of "being a language reference" to the little ones. Speak your mother tongue with them, the toddler will learn it at their pace (unless there is an issue in the development of the child, which then a specialist should be seen).
To the extent of all researches conducted with young people and their language development, all kids need is to have a consistent reference at home that they can relate to when developing their multilingual brain and speech skills. So, speak the language of your heritage, your mother tongue, and allow them to have the same opportunity.