You should retwist starter locs approximately every 4 weeks, especially during the first 3 to 6 months of the starter phase. Some recommend retwisting every 2 to 3 weeks for the first month or so to help set the locs, but be careful not to overtwist as this can cause thinning and breakage

. Here is a general guideline for retwisting frequency based on loc phases:

• Starter phase (0-6 months): Retwist every 4 weeks, possibly every 2-3 weeks during the first 4-6 weeks.
• Budding phase (6-12 months): Retwist every 4 to 6 weeks.
• Teen phase (12-18 months): Retwist every 4 to 8 weeks.
• Mature phase (18+ months): Retwist every 8 to 12+ weeks

Factors that influence how often you should retwist include your hair texture, thickness, hair growth rate, and lifestyle. For example, thinner hair may require more frequent retwisting, while thicker, coarser hair can go longer between retwists

. It's also important to avoid over-manipulating or retwisting starter locs too often to prevent damage. Washing starter locs is generally recommended every 3 to 4 weeks to avoid unraveling, and moisturizing them with light oils helps maintain their health

. In summary, a safe and effective retwisting schedule for starter locs is about every 4 weeks, adjusting slightly based on your hair's needs and how well your locs are forming.