I started Obagi Nu-Derm one week ago. How red should I be? (photo)

What strength tretinoin are you using and are you also using a moisturizer afterwards? Obagi makes one that comes in the normal/dry kits called Hydrate. You can use that over the tretinoin to combat the dry/irritated skin. However, it takes skin about 12-16 weeks to adjust fully to the Nu derm system and the redness and irritation are a clear sign that the active ingredients are working as they are supposed to so your best bet is to just stick with it as best you can and if you continue to stay very irritated, consider using the moisturizer before the tretinoin as it will buffer it a bit. Other options are to reduce the strength of your tretinoin or space it out to every third night.