Sounds like I am just a few weeks ahead of you in this game! I would personally suggest building up to the full dose over a week or two as I found 400mg/day too much for my stomach at first. Eat lots with the tablets, and make sure you take a full glass of water too. Ginger biscuits can help with nausea, and whatever you do, don't lie down for an hour after taking the tablets (you will burn your gullet!). Have lots of warm baths, and don't panic if you get worse for a few days - it will hopefully pass like mine did.
Fingers crossed for you, and hope it starts making you feel better soon!
Kirsty