split the amount you want to invest place one half in an order...

split the amount you want to invest place one half in an order the day week or whatever before you expect the announcement then you are primed and ready you can always pull it if the announcement is negative in alot of cases the announcement wont come out at exactly the moment the trading opens for the company. If positive well then you may well be staged for good entry. the second half you can use to exploit the a negative situation by averaging down if you don't get to pull in time or you can ride it up by placing a second order, or even wait for the price to roll back slightly as can happen when the dust settles a post announcement.

Or you could consult the stars, chicken entrails, crystal balls or the I Ching for an answer they are all about as accurate as most peoples TA.