Heey..my engagement was on 4th April 
I got a ring from my MIL for the baat pakki, which was in November '09..she insisted on getting me one bless her although i said that its ok if she doesn’t as i knew i’d be getting one on my engagement. But she wanted me to have one so its all good I helped pick out both my baat pakki ring and engagement ring.
My MIL left it completely upto me to choose my dress and colour combo, the only thing she was responsible for (alongside my fiance ofcourse!) was paying for it lol. She wanted me to have it designed how i wanted..which was very sweet of her.
There was about 180 people at the engagement as it happened on the same day as my brothers Valima..both functions went extremely well alhumdulillah
InshAllah the shaadi is being planned for oct/nov 2011 n to answer your last question i considered myself engaged the day my rishta was done!
The actual rasm was simple..he came in with his family, they brought mithai etc..i was then brought in by my brother and sisters..we had our rings on this gorgeous lil ring cushion my Mum had made. We then exchanged rings, everyone clapped and hey presto we’re engaged! 
After that we had a simple photoshoot and lots of family dancing. it was a great day alhumdulillah
Whens your engagement?