Greg,
I think the guys may have misunderstood your query, obviously you need to contact the AW to make the arrangements for the outing.
The reason that you need to contact an Assesor is to make sure that you understand what DSC2 is all about and make sure that YOU get the portfolio filled out correctly. Don't forget that it is your responsibility to ensure that the paperwork is correct. More DSC2 problems arise because of bad admin than bad skills in the field.
Do give an Assesor a call (although you may have left it a bit late now - I would try just after dark this evening).
Do make sure that you and the AW both make a good job of the paperwork.
And, please, please, do enjoy your witnessed stalks and go into the process with a positive attitude.
Don't forget that it is not a test, simply an opportunity to demonstrate your skills and knowledge whilst there is someone else present to witness and assist in the recording of the event.
Also, don't forget that you can gain a fair bit of evidence even if you don't get a shot, for example, you could stalk into a shooting position on an out of season deer and indicate to the AW that you would be happy to take the shot, assuming that it is safe and achievable, then you will have a stalk in the bag which will come into play later if you shoot a beast from a high seat or shoot two beasts as a result of one stalk.
Good luck, hope that you have a succesful weekend.
JC