As you will gleen from this forum it is a bit no no to weigh other than your official weigh in, from experience it will make you complacent if you see a mid week gain and more likely to go off plan if you see a gain and these mid-week/own scales weigh in's are never accurate, so do yourself a big favour and stick with the plan and wait for official weigh-in I am sure you will be pleasantly surprised.
Good luck - believe in the plan, it really does work if you follow it!!