By "soon", I think you mean 12-15 months. And even then, it will take a further 9-12 months for demolition to be complete, followed by around 18 months of foundation/piling work before the core can start to rise. This tower is unfortunately still a long way off...
Far more exciting in the short term is the Leadenhall Building, which is starting work in January 2007 and will take only 2 years to build.
This project is now in doubt, thanks to the heritage body UNESCO, who are worried it could spoil views of the Tower of London (despite a lengthy planning procedure in 2001-2002, followed by an even longer public inquiry in 2003 which cost £10m and proved beyond doubt that the Shard would have negligible impact on the Tower of London). UNESCO seem to feel that London is a "museum city" like Rome, which can never change or develop in the future.
Transport for London - who were meant to be taking the office space as their new headquarters - are rumoured to be under pressure to cancel their pre-let.
In addition, a bitter row has broken out between the partners who are funding the Shard. It sounds like they will be going to court.
In my opinion this is beyond a joke now. It's a farce of epic proportions. So much time, money and effort has been invested just to reach this stage. PricewaterhouseCoopers are vacating the current site in July, funding was secured, and construction was all set to begin immediately afterwards... but the whole thing is now in doubt.
I am totally and utterly fed up. Kiss goodbye to this stunning, beautiful, world class landmark -
if it's true, that the UNESCO decision has in fact meant that the Shard is now not going to happen, that is indeed a shame (i don't personally agree with them on this one), but lets hope that it's a good sign for the same thing happening at Potters Fields (where the new blocks of flats shouldn't be built as currently planned).