Will my broker do the assignment of 100 shares automatically if the shares drop below my strike price? Let's say if my expiration date is 30 days away, and stock price already drop below my strike price the first 2 days. Will it assign? Or does it assign on the day of expiration? If it only allow us to buy the shares at expiration date, does that mean even if the stock price drop to $0.01 cent, I'd still have to buy the 100 shares at the strike price minus premium?

Also does that mean the 100 shares will only get assigned if the "closing price" on Friday is below the strike price? So I get the shares after hour on Friday?