It depends on what you're working on and looking for. There's a lot of relatively positive media spin around at the moment that's suggesting that Brexit isn't as big a deal as people thought it would be. I think the reality is that no-one will have a full understanding of what's going to happen until the UK triggers article 50 and properly starts the negotiations to leave the EU.
From experience - there are still a lot of jobs in the London market. There are some companies that are scaling back their hiring a bit, but from an investment point of view and from a company point of view, there's still optimism and a general belief that even if the Government fucks things up in the negotiations, the UK is only a short hop to Dublin, Berlin, Paris, Lisbon or any number of other European cities that will welcome companies in with open arms.
In short - the job market is still pretty good. If you're not in any mad rush, then I would hold off and see what happens in the new year (which is when they're apparently going to start the negotiations to leave). The people negotiating on the UK's behalf are not the sharpest tools in the box, so it could start to fall apart a little, but realistically, London is a major global city - it will remain relevant from a business and investment perspective for a while yet...