It is possible to earn some curation at 15 SP but not terribly likely. There is a minimum 'earning' requirement of 0.001 SP on a curation reward where anything less than this is instead a zero (since this is the smallest split possible for steem.) Essentially you'd have to getting your vote in before any big voters, then having the post earn a large amount of $. Also, this all is assuming your vote power % is at or at least near 100%.

Typically (because of this) I recommend for people starting off (with the 15 SP) to focus more just voting for things they like simply because they like or want to support them versus for curation.