Its not a lot if he needs it all!
Toby was on gaviscon every bottle but we've stopped it and changed him to SMA staydown milk because its heavier than SMA Gold with gaviscon and stays down better. And he's more comfortable with it and drinks more of it. He'll finish 6oz bottles of staydown milk but only take 3-5oz of sma gold with gaviscon.
On the weaning thing... Toby is 4 months old next week. OH is *desperate* to start feeding him. But I don't think Toby wants it yet so I'm standing my ground. I mean, he watches us eat but it's because he's a curious boy, not because he's hungry. He goes 4hrs between bottles and doesn't get hungry between them. That and the fact that he's still suffering from reflux with regular formula makes me think he doesn't need it and his stomach isn't ready.
For teething, I might give him some cold carrot to chew on, to get him used to flavours without actually eating/digesting anything. But not yet. Maybe in a few weeks. Then we'll wait and see. When he's ready to eat, he'll let us know.