Andrew Wadsworth, director of Waterhouse which is developing the site in partnership with Resolution Property, told business leaders in the town that the next chapter in the regeneration of the old brewery site would take around 20 months to complete.
Last month it was revealed Galliford Try had been awarded the £27million contract to work on the next stage, which will see 132 apartments and 15 new shops added.
At a meeting of the Dorchester Chamber of Commerce Mr Wadsworth also revealed that it was hoped the bronze dray horse statue planned for Dray Horse Yard would be installed over the Easter weekend and that fundraising would start in the summer for the Malthouse Theatre.
Mr Wadsworth told the business representatives that much of the Brewery Square scheme was about bringing to Dorchester things that it simply did not have before.
These included a town square, with an estimated 4,000 people enjoying Carnival Day around the fountains and the skating rink attracting around 6,000 people over the winter.
Mr Wadsworth said that five shops in the main square have been let and an offer had just been accepted for the remaining unit.
He said: “We have managed to get quality names and we are holding out for that level of quality with the rest of the development.”
Mr Wadsworth added that all 66 apartments in the previous phase had been sold and around 20 per cent of those in the stage about to start had already been bought off plan.
He said the next phase of the project, which includes the Brewhouse Hotel and Malthouse Theatre, would roll on from the current phase.
Mr Wadsworth said the hotel itself was a £10million project while work had been going on for plans for the theatre for around 12 years.
He said Brewery Square would be donating the building itself and had spent around half a million pounds on preparatory works for the 450-seat theatre and would be handing it over to a charitable trust.
Mr Wadsworth added: “We have just finished a new feasibility study and are hoping to launch a fundraising campaign during the summer.”
Mr Wadsworth also dismissed rumours that the Odeon cinema was due to close and becoming a bowling alley.
He said: “It's not going to close and it's not going to become a bowling alley.”