How much for a retainer?

[Octaviapink]

I have a new client who wants to take three days of my vacant four days to start with and then move up to all four after three months. I almost certainly can't get anyone for that one-day slot for that time period - would I be justified in charging a full price retainer for the fourth day until she takes it up? Or do you think I can only charge a percentage and if so, how much?

I usually charge a 50% retainer in that circumstance. :)

Thanks leeloo - yes, I thought I'd have to settle for 50%.

I charge 50% during the holidays for the child I look after as her mother is a teacher, but this is on the understanding that they can use the place with some notice. I would charge between 50 and 75%