First time doing online stock trading so forgive me for the noob questions..... 

Ordered some stocks through maybank stocks online at 3pm.... guess it went into the buy queue....

Then when I check the status at 5pm, it showed "All matched" at around 3:02pm...... however, I think the transaction hasn't gone through yet....

Can I cancel the order or should I just wait for the "buy order" to go through tomorrow?

And can I actually queue any orders tonight?