How do 2 strands actually loc?

I just had my hair stylist start my locs with two strands. I’m new to all of this, so I’m wondering just how these two strands will turn into locs/when to get a retwist.

I just had my hair stylist start my locs with two strands. I’m new to all of this, so I’m wondering just how these two strands will turn into locs/when to get a retwist.