We find many different terms to describe when and how we learn languages.
We call those who learn to hear and speak different languages from birth (or shortly afterwards) simultaneous bilingual. If other languages are learnt at a later stage, we speak of successive or sequential bilingual language acquisition. The point in time from which one speaks of successive is a matter of debate. It is often defined that children are considered to be successive bilinguals after the age of 3. At this point, one can assume that basic language skills are present. Many grammatical rules are mastered and the vocabulary is already well developed. Furthermore, there is empirical evidence that this acquired language competence of the first language has an impact on the acquisition of the second language. Studies also show that language development differs from simultaneous bilingual children. The term L2 learner is used in the context of foreign language teaching. A fundamental difference is that the language is explicitly taught here. The children learn rules on how to use the language.
Well, which category (or categories) do you fall into?
If you want to know more about bilingual language development, read this blog or watch my talk on YouTube.
All the best,
Blanca