How early can 4 month sleep regression start

- How late can 4 month sleep regression start
- Can 4 month sleep regression start at 12 weeks
- Can 4 month sleep regression start at 3 months
- Can 4 month sleep regression start at 10 weeks
- Can 4 month sleep regression start at 14 weeks
- Can 4 month sleep regression start at 13 weeks
- Can 4 month sleep regression start at 5 months
- Can 4 month sleep regression start at 3.5 months
- Can 4 month sleep regression start earlier