Amazon is moving forward with a plan for a prospective distribution center and warehouse in Charlton, which the company estimates will include a $300-million investment and produce at least 1,000 new jobs, developers and Brad Griggs, senior manager for economic development at the online retailer, told selectmen Tuesday night. The Charlton Board of Selectmen, who hosted a special meeting for a project introduction, did not know until the meeting the proposed tenant for the facility at 52 Sturbridge Road was Amazon. The project is being developed by Bluewater Property Group of Pennsylvania and New York, as well as Bay Colony Properties of Waltham.