The placement time of CFD traders depends on whether you’re doing DMA CFD’s or not.
If you’re actually participating in the market open, and you want to get in on the opening market price, then many platforms will let you place them at anytime when the market is closed.
Some don’t however, and you’ll have to be there in the 20-30,minutes before the open to place your order in then to get the opening price via the opening auction.
So for CFD trading on DMA, it does depend on your platform an broker.
For limit orders, eg a buy limit at a price BELOW the current pmarket price, your provider may do so in ORDER of PLACEMENT.
So in this case, it pays to get in early. Eg if you put your order in when the market is closed at 5pm, compared to someone who does it at 10pm, then you will get in first. The 10pm guy may also get into the CFD trade, but he may not if there’s not enough liquidity.