The halving is not planed. It happens when it happens. Basically the reward is halved after every 840,000 blocks are mined. It takes on average 2,5 minutes to mine a block.
13,916 are left until we reach that. Using a little math magic and we get 24 days and a few hours... It's about the math and mining power, not a plan some people made.
Is it worth buying? Maybe. Nobody knows. I repeat, nobody knows. Use the little freedom you have left and make your own choice.
Personally I think that after serious corrections over weeks, since latest peak, Litecoin now is worthy altcoin to buy. I don't think Litecoin might surpass its latest peak, but it might be able to move close to that price range. And, such recovery before the halving is enough for me. Moreover, the things will happen with Litecoin closely before halving time might be a good example for what might happen with bitcoin halving next year, that is what I am more interested in.