"mined balance will be avail in 435 blocks"
The intention is to prevent pump & dump
OK, I was eager to start burning but now I have to wait whole day maybe,
also there is possibility that coins go void:
If it fails to get into the chain, it will change to "not accepted" and not be spendable. This may occasionally happen if another node generates a block within a few seconds of yours.
You should now have a number of confirmations on the mined block, so it will eventually be added to your SLM balance. The above text is really a standard notification in regards to how PoW blocks are generated and is much more relevant to coins with lower block times also using fewer confirmations, however this is always applicable to PoW block generation - mostly when solo mining.
Trying to solo mine PoW blocks is still well worth the effort. It might take 2 days or more to find a PoW block at the current difficulty, however the overall reward is likely to be much more than if you could mine in a Slimcoin pool for the same duration at present. When pools are set-up for Slimcoin you can expect that their will be even more people mining and the network hash rate will see a big increase, again lowering the PoW block rewards.
Building a working pool for Slimcoin requires the technical know-how to get it up and running and working properly. This is a new kind of algorithm / block reward system - thus we are likely to see much fewer, although quality pools being set-up - it will be very similar to how Primecoin pools (and mining) evolved in this regard. People are busy with getting a pool up and running, for sure.
Again, its still well worth trying to solo mine a PoW block to get started with PoB.