For recent historical perspective, after 9-11 the airline industry was in turmoil, it took a good 2 or more years before the upturn happened. This was against the background of a strong world economy...but I would venture a year or so may be optimal timing.
From someone who qualified during the 9/11 industry downturn in 2001, it was 2004 when I got my first job and before any signs of recruitment appeared...I would disagree 'a year or so would be optimal timing', i'd make it 2 minimum, maybe more, there is a HUGE unknown as to what the next round of recruitment will be like - 'Pay-to-Work' Morons or high experience 2000 hours+ only...
Keep an eye on Boeing's 787 progress, any furthur delays may just result in the UK market been flooded with pilots as certain airlines refuse to carry its surplus in a year or two. These will be pilots with multiple jet types and 1000's of hours...so much more to come!