Something i saw happern the other night, and whether it was intentional or not it works damn well, apologies if it's been mentioned before.
It involves intentionally not completing the travel time researchs. Basically, one fleet launchs a fleet (BS in this instance) at eta 11, this is generally covered. Next tick however another,fleet is launched to land on the same tick at eta 10, this again can be generally covered. On the eta 9 several big fleets are then lauched, which means additional defense has to be found. Generally speaking though due to the now size of the wave and the nature of anti bs this round this is difficult to get hold of. Additionally, any anti bs that had been sent would probably have to be recalled as losses mount up, meaning that defence fleets have been pulled out for several ticks, depending on whether or not the defenders are online to pull their fleets.
This therefore is a great way to tie up defence fleets for the night, though at the cost of TT research. Obviously the target would have to be big enough to warrent the use of so many fleets, but it can be a real pain for defenders
Edit: i suppose similar to this but with the travel times completed would be to send differant eta ships that lnd on the same tick but launch at differant ticks