Factor 1: Child readiness. The most important predictor. Look for: staying dry 1–2+ hours, showing awareness of being wet, able to follow 2-step instructions, showing interest in the toilet, can pull pants up/down. When 3–4 of these are present, the timing is right from the child's side.
Factor 2: Family stability. Starting potty training during a family move, a new baby, starting at a new daycare, or a major illness sets you up for struggle. Potty training requires consistent attention for 2–4 weeks. If your family can't provide that right now, waiting for a calmer window is legitimate strategy — not avoidance.
That said, children train successfully in every season. If your child is ready in January, start in January.
When you're ready to commit: Having the right tools before you start makes the first week significantly smoother. The Benny Bradley's Potty Training Watch + Board Book bundle is a great "launch kit" — the book introduces the concept in a story, and the watch keeps the schedule without you having to be the reminder every hour. Available for girls and boys.