You will need a high chair when your baby can sit up unaided and has good head and neck control, usually around 6 months when weaning begins. It is worth researching now because the best chairs sell out regularly.
Buy the Stokke Tripp Trapp if you can, we bought one for each of our boys. It is an investment, but it lasts a lifetime, supports proper posture from day one, and brings baby right to the family table. If budget is a concern, and that is completely reasonable, the IKEA Antilop at around £20 is genuinely excellent, just add a £15 footrest from Amazon. The Joie Multiply is a solid middle ground if you want more features and a few more years than the Antilop without the Stokke price. Tip: Tripp Trapps hold their value brilliantly second-hand, so check Facebook Marketplace and eBay where they often go for £80-120.
When they can sit up unaided with good head and neck control, usually around 6 months when weaning begins. Some babies are ready as early as 4 months.
Proper posture support (feet flat on a footrest, hips at 90 degrees), easy cleaning (minimal crevices), and safety (five-point harness, crotch post, stable base).
Feeding therapists and dietitians increasingly recommend chairs that bring baby right up to the family table rather than using a tray. It helps babies feel included in family mealtimes and supports a healthy relationship with food.