When is the right time to take a baby to the beach?

My twin baby boys are 5 months old and I really want to take them to the beach (we live in Australia), I’m a first time mum and I’m not sure when the right and safest time is to take a baby to the beach, I see some newborns at the beach but then I see toddlers at the beach I just don’t know when it’s best to introduce babies to sand.

Any suggestions?