I have no doubt what you have been told. Infact I believe the original date was the 14th. However you know what BA are like for changing there mind.
I work in IFS. My cousin in Sales and Marketing and my best friends is i ops and planning. They have all been told that the announcement will be on the 1st.
Also WW and Martin Broughton have both said in press reports it will be announced on the 1st August
However according to my mate in ops no 747 will be grounded as it will cost more money to store them in the desert than to have them at LHR operating and on standby. This is because of the high number of US carriers already taking up the space at the current storage fields.
Also they will be needed to cover then on average 4 x 772 going for new CW and AVOD reconfiguration from October to March
He did say something very interesting BA want to dispose of the 3 772's in the high F config as they would cost to much to reconfig when the new F is launched in March 09. Also BA want a standard size F cabin (believed to be between 10 and 12 seats on the 747's and the F embodied 772's. Also they are the only 3 that aren't ER varients.