...what age did you start and at what age was your LO able to ask for things using signs (rather than just copying you when you make the signs)?
DS is 5 months and I'm starting to sign 'milk' to him (as a way of getting myself in the habit of doing it, since I've read that it's only from around 6 months that babies start understanding that things have names). I'm hoping that eventually he'll be able to ask for a feed, since his hunger cues are very difficult to read at the moment - but I'm assuming that it will probably be a few months down the line before he is able to ask for food with signs.