First sous vide cook - how long?

Got a sous vide for Christmas, and it seems that everyone here loves to cook pork, so that will be my first cook. The center cut loin chops at my grocery store are not particularly thick - 3/4 inch or so.

I see many people recommending a cook temp of 137, but there seems to be a wide range of cook times, from 45 minutes to 4 hours. What do you guys think?

Thanks!