Accusation of Bullying...How long for school to respond?

[MrsFruitcake]

Back story...

My DD (9 yesterday!) came home on Friday with a large bruise on the top of her leg, on the fleshy part where the thigh meets the buttock. She says that a boy in her class was trying to kiss her and she refused. His response was to push her backwards into a low brick wall and hold her there before she struggled free. She went and told a teacher but as far as she was aware, nothing was done.

The bruise is now about the size of a satsuma, livid green and purple and you can see the line where the top of the wall dug into her leg. She says it's tender and painful.

So, yesterday morning, I rang the school (DD gets on the school bus which collects DCs from outlying villages so I don't get to go into the school often) and explained that I was concerned about the way in which this was being handled, DD had expressed worry about seeing the boy again etc etc. They assured me her teacher would call back but the call never came. So last night I mailed a picture of the bruise and a brief summary of the problem to the headmistress. I got an auto-response saying she was out all week and so I mailed it to the school office instead (this was at about 5.15pm last night). DD said that she had seen the boy in question yesterday and he'd told her that if she's snitched on him about Friday, he was going to hurt her again. She was understandably wary about going to school this morning.

So far today, I haven't heard anything. How soon should I expect the school to deal with this and how long should I wait before escalating it again?

Is this an ongoing problem with the same boy, or is it a one off?

Common sense and politeness would by now have said there should have been some response, even if it was just thank you, will get back to you.
If you have not had a reply by tomorrow morning I would suggest you need to do something. The problem is what.
Having escalated it to the head teacher in writing (email) you have partially invoked the complaint policy of the school. My inclination would be to send another email to the head teacher saying that you wish you other email to be considered as a formal complaint about the school and that you would like a written reply on the school's investigation of the incident. You also need to include the latest information about the threat made by the boy.
Whilst the head teacher may not be in school all week, I would expect them to be looking at emails and in their absence somebody must be acting as head teacher and should be dealing with this.
To be honest I am not sure how much will be made of the first incident, it is one of those situations where it is very easy to get into a 50 /50 blame situation. What is far more of concern is the threat made by the boy subsequently because this suggests a pattern of bullying and probably not for the first time.
You then do need to give the school time to come back to you officially with an explanation of what they have discovered about the incident. By time I would say a maximum of a week.