I have come to learn over time that everyone has a different definition of being bilingual. Who knew! But I suppose everything is like that. Depending on who you are, how much time you have, where you come from, what pressures you are working through...your approach and goals will be different. It really does not matter; the a effort alone is already something to be proud of.
At some point, I realized that I had to decide whether I wanted to take the bilingual or biliterate route; the latter involves speaking, reading and writing in the 'target' language.
Btw, when I speak of the 'home' language I am referring to the language spoken in the home. The 'outside' language is that spoken largely in the country, school, with friends, etc. outside the home. The 'target' language is that which you are trying to master.
I do not know if my decision was conscious, but if I look back I realize my high expectations have put us on the path of learning to read, speak and write in Spanish. Therefore, I don't just expose them to the spoken language, but I invest a healthy amount of time teaching them to write and read in Spanish.
There is no right or wrong way for exposure. I would suggest trying various ways, until you (and the whole family) feel comfortable. Remember this is a way of life not a momentary diet, so pick something that fits your family's lifestyle. As you think through it consider, how much time you will dedicate to it, what is your fluency level, what works for your family, do you have any other support, etc. You might find some helpful tips in the "getting started" section of our site.