Like believe I think it's usually better not to think too much ahead.
Exceptions for me are coats and waterproof gloves and boots, ebay before it's too cold, but not months ahead.
Underpants and socks get bought at Christmas when my PILs give us M&S vouchers. Maybe updated pack of socks in the summer.
Ds has 4 pairs of shorts, 2 pairs of black jeans that he wears in and out of school until they decide to crack down on uniform 4 school shirts, 2 school jumpers, 10 pairs black socks, eight pairs pants; approx 8 tshirts (mostly presents), 5 long-sleeved tops, 1 hoodie, 1 raincoat, water proof gloves and trousers; warm boots, trainers, school shoes, fake crocs; school pe tops and tracksuit, club cricket kit, club athletics singlet, 2 swimmers. Dressing gown, one reasonable set of pjs, a few outgrown remnants of pjs that he still wears. He's grown out of his warm coat, thanks for the reminder... It's the sports and pe kit that cost, plus i buy him proper trainers as his feet are weird and he gets orthopaedic problems.