Age for using connecta accessory strap

[Summertime10]

Hi all, I'm excitedly waiting for my connecta arriving with the postman today. My question is- will I need to use the accessory strap to narrow the width? My son is coming up to 17 weeks old and about 13/14 lbs ( tracking just above the 9th centile).
Thanks!

Depends on how long their legs are really. It should go knee to knee without bunching. If it bunches, sinch it in with the strap. IIRC, I needed to use the strap at that age.