EEA4 - six months clause

I posted the application on 15/01/14, Special Delivery

Royal Mail confirms it was delivered on 16/01/14

UKBA sent a 'generic' confirmation of receipt letter on 17/01/14

UKBA sent a case-specific letter on 02/02/14 where they say that the application will be
considered 'within six months'

As far as I understand, six months start running since date of receipt by UKBA (16/01/14)
not from whenever-they-decide-to-send-us-a-letter (02/02/14)

Any opinions and experience on this? When does the six month period start?

And do requests for additional documents extend this period somehow?

I know the six month deadline is frequently broken, but we need to travel out of the UK in
late July and it is crucial that we get the documents back by 16/07/14 not 02/08/14

Thanks for advice,

Melafafon