bigwig did not (no offence intended) give you a detailed reply.
The easiest solution is to look at level 2 (along with pbb which I have lost due to account problems with no response from ADVFN since 9am !!) and look at trades and make an informed decision. If you expect good news at the press conference then perhaps you should hold.
If however, you believe in the old adage "buy on rumour sell on fact" you may be better to bail prior to any announcement, bearing in mind todays percentage rise is substantial.
I would say there are little facts in this thread and lots of speculation. Make your own mind up or you will never forgive yourself, let alone the person whose suggestions you follow.