2009 x Type spark plug change interval
 

I've tried searching for this but couldn't find anything definitive. Would anyone have a workshop manual extract that details the recommended interval for changing spark plugs?
I think it might be every 70K Miles (112,000 KM) but I'm not sure. I have 103,000 KM on my car and I'm wondering how soon I should be thinking about changing the spark plugs. It's a big job (necessitating removal of inlet manifold) so I don't want to do it too early if I don't have to.

Spark plugs
 

112,000 km 0r 70,000 miles.

Thanks for the extract jaapavanthoff.