dd is 8 1/2mths we put her down to bed as usual at 6.30pm, anyway she has this habit of kneeling and rocking backwards and forwards next thing we know she is sitting up 
I couldn't believe it (we then had to lower the cot down a notch!) put her back to bed and went downstairs heard her chatting away went up and she was sat up again grinning away, she is growing so fast and doing different things everyday, totally wonderful and amazing