My simple answer to this question is as soon as possible! Too often a Quantity Surveyor is only brought in when there is a crisis. If a QS is engaged early, then the crisis may be avoided altogether. Engaging with a QS early to understand how a QS can help is vital....

I always say, ‘if you set it up a project properly it will run itself’. Putting the effort in right in the beginning will save you problems later. By that I mean by engaging the right architect and contractor as well as making time to set up the contract properly will...