This depends on the season. Wedding season and sacrament season tend to get booked months in advance (August - March)
For all other months, I would recommend to make your enquires from 4-6 weeks in advance.
On the odd occasion I might be able to take on an order within 2 weeks notice depending on the amount of work involved in your chosen design.
In the case of larger orders yes delivery is a service I can provide at an additional fee.