With the current difficulty, it will take your 1.5K balls a little while to stake.  They will continue to accrue interest while waiting to stake, so your not losing anything, except access to them. 

   Based on the design of Balls it could take a little while for the network to level out.  At first everyone was staking almost as soon as the coins were mature.  Since they were less then 48 hours old, every stake was getting split into smaller and smaller stakes.  Then as everyone started pulling Balls from the exchanges to stake, the larger stakes were happening fast and the smaller ones took longer.  The larger piles are being split, and the smaller piles are gaining weight.  When the smaller piles finally stake, they will not be split because the time is greater then 48 hours.  Eventually, if no one added new coins to stake, all of the stakes would be close to the same size. 

   This is all done to keep the network flowing smoothly.