I started my NQT year in September, but I remember vividly what it feels like to be in your boat! I did pretty much what both of you are planning, but I spent most of the first week back doing PSHE-type activities, and lots of active, get up and go maths which the children didn't realise was "proper maths" but which let me get to know the various personalities, and the dynamics of the group of pupils. It's probably easier to do that sort of thing in September than now - I think you're both right to have a "new class" day, and then hit the ground running on Wednesday. The reason I'm typing this is to let you know that, however worried you are, the first few weeks will whizz by and then you'll be settled into your routine in your classroom. You'll notice things that you'll do differently in September, but you'll be great!