I don't transition to the table till they have developed a few table manners as in no longer need the tray to catch all the messes for one thing but rarely before 18 months. Each child is different and it depends on how well they balance, can get on and off the chair. I start by having them at the table when we do circletime or craft and observe them sitting there colouring.

I will start with snacktime which is shorter and generally less messy so sitting at the table for a couple crackers not a meal. No bottles are ever served in highchairs or at the table. A cup is offered. If not drank then it goes back into the bottle and after everyone else has finished and gone on to play the "baby" can sit on the floor in the kitchen with their bottle while I clean up. We are talking a child over a year here not a real infant.