A market order means that the trade will be executed at the first available rate when the market opens.
You will be able to open a market order whenever the market is closed; this is true for stocks as well as for currencies, commodities and indices.
This also means that you can now copy over the weekend and if you choose to copy open positions.
(All open positions will be copied when the market opens).
In addition, it’s important to notice that with this change, the amount allocated to an order will not be available for trading, since the order amount will be considered as “reserved” equity, unless you should cancel the order.