There is a "Check" option on the portal to see when Nyriki is due to emerge at a Hunter area around Gielinor. This will also tell you where he will emerge. Then, when Nyriki has appeared you can teleport straight to him and start the D&D. (You can teleport to the spot where Nyriki will appear before he appears too if you would like to do that.) Note: You can only use this portal 3 times a day.