When will my Betta make a bubble nest?

I just bought a female betta for my male whose almost a year old now and i decided i wanted them too make.. i just introduced him to her in a smaller tank with a divider in it, at first he didn't seem to thrilled with her and tried to attack her at first but a few hours later and he doesn't seem so worked up and remains quite at his far end of the tank, only very once in a while going over to investigate.. she on the other hand seems very interested in him following him where ever he goes, i believe hes shown some interest by turning side ways and fanning out and jutting from side to side... so im curious to know if this is normal behavior and if so when can i expect him to start construction of the nest?