Rhubarb in overdrive?

Please can anyone give me some advice, I'm new to gardening and planted a crown of rhubarb at the start of the season. Its now grown huge, over a metre tall and probably 1.5 metres across, with loads to shots still starting to grow. Everything I've read says not to harvest it in the first year, however it is starting to take over the corner of our garden and putting everything else in the shade. 

Please does anyone know if it will do any harm to harvest some of the largest stalks this year or should I do as every book says and leave it to just grow this season?

Any suggestions will be greatfully received.

It's tempting to take a few stalks, but resist. With the heat and rain, it's building a big root system right now, and to start picking will diminish this growth. Next year you should be able to start taking a few stalks.
And while you're looking, mark out the area the plant takes so next year's plantings of other veg/whatever won't be shaded by the leaves.

I never harvest any at this time of year anyway as there is too much oxalic acid in it and it will give you a tummy ache 

I've wondered about this..................

Is it just the overgrown pieces that have spent weeks stewing in their own oxalic acid that should be avoided or should I suppose that new shoots are also high in oxalic acid ?