there is no ETA. lightning developers have taken the position that there is "no rush" considering how much value is expected to be stored in payment channels. they are very concerned about ensuring that no funds are lost as a result of using the LN protocol.
having said that, it's pretty widely expected that LN will be usable by the general public sometime this year, likely in a matter of months. the next major step is to complete wallet implementations. we're already seeing lightning transactions on the network; now it's mainly just a matter of releasing the software.
It's not like there's an actual "official LN launch" date or anything like that. Rather LN will be "launched" when people feel confident enough in one or more implementations of LN to use it on the main Bitcoin network. In fact, you could consider LN to already be launched as there already are people using LN on the mainnet. Of course those people do so at the risk of their money, but nonetheless, the software mostly works and there are transactions occurring.
Could this be the reason there's been an increase in the rate of larger than average kB transactions recently? With ~195 MB of transactions confirmed in the past 24 hours across ~325,000 transactions, that puts the average transaction size at 600 kB (much larger than the 225 kB of a typical transaction).