When do bettas begging making bubble nests?

Well my male betta,Right when I got it 1 or 2 weeks later it had bubbles,calleds bubble nests they are together on the side of the bowl, and after that it had over 75 bubbles! I saw him make one a couple of times it looks like he is reaching for air and goes on the surface of the bowl? so, 1-4 weeks he starts makeing them,And he makes about 75 in 1 week or 2!