Start Small, Then Grow the Team
When starting a project, aim for two experienced developers and one intermediate. All members of this core team need to be very good communicatorsnot only will they be involved in the project scoping activities, but they'll be the people who have to explain the overall requirements and architecture to new team members who are brought into the project.
By starting small with an experience-heavy team, the project scoping and design exploration activities can proceed rapidly. The team should only be expanded when the core team has created an overall project plan and worked out the ideal team configuration. For best results, make sure that the rest of the team is brought in together, on the same day. True, the next two weeks will be spent briefing the new team, but it's very important that the original core team take the time to set the scene and expectations for the whole project. Bringing new team members in one at a time is a mistake because later arrivals will get shortchanged on the project briefing.