You should call your broker before the open to find out what their policy is. Some brokers allow clients trade greys online; others want clients to call in their trades. Usually they don't charge extra for the call. Some allow both buys and sells; others, only sells.
The stock may not start trading at 9:30 sharp. DTCC needs to put out a reinstatement notice first. It sometimes does that before the open; other times it doesn't. Occasionally, though not always, brokers hold up trades till the notice appears. That can happen as late as 11:30 or noon.
When the stock does begin to trade, the first transactions are usually very low. The price may tick up a bit over the next few hours. Since there'll be no bid or ask, your only guide will be time and sales. What you want is to see is for the stock to establish some kind of trading range. Use that to choose a price that may get hit. If it's too high, you may not be filled.
So... Get a feel for what's going on before you take the plunge.
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