The official website of St Lucia citizenship by investment program informs that only the application processing usually takes up to 90 days. Some legal firms promise to obtain and send St Lucia passport to the applicant in 90 days. In reality the whole process to get St Lucia passport normally takes 3-4 months.
The processing time depends on the documents that you submit together with your application. All the documents must be translated to English, their copies notarised and apostilled . If your documents arouse no doubts of the immigration authorities, your application will be approved quickly.