How much is too much?

I hear over and over that one of the biggest mistakes people make is doing too much during their taper.  it's so hard to set back after months of go go go.  and I can see where that would be so.
When does the taper start?  Because Ive not really done any less yet.  Im following the training plan still, and I ran 57 km this week (counting long run).  So does the taper start this weekend?  Run less next week?

Some of my workouts were pretty strenuous too; still running with the Cross Country team and on their hard workout days I run with them.  Today we did hills in the park on their course for Regionals; VERY hilly.  So a total of about 8 long hills and 9 km of rolling trails.  Next week they are going to be racing on those hills and I hope by that time the hills are so familiar they are nothing.

9 km, 1 hour (counting time I stopped to talk to kids and dragging my own 2 kids around the first 2.5 km.  Maggie joined me on the entire run and she was SO good. we met a couple of other dogs and she barely gave them a glance. It was good of her. 

16 km tomorrow? Or Sunday. It's supposed to be tomorrow.

Lately of course all I can think about is the upcoming Marathon. it's all consuming. I can't do THIS, I have a marathon. I have to do that, because I have a Marathon. Don't ask me to think too much about something else, I have a marathon.  LOL only someone who has done something big can really understand.  And Im sure anything this big is the same; it's just really a big thing ;) And Im pretty sure most people don't understand how big.  Because to most people I know, runners are crazy and marathons happen every day. I dunno, it's big for me.