The skin process after IPL takes about 2 weeks to finish. What you should expect is to see the pigment coming up to the surface and being pushed out of the skin, so yes, it will look darker as the pigment is coming to the surface. Give it 2 weeks, if no result go back to your doctor.
There are many variables to consider when speaking about photofacials and normal skin reactions. Ideally, after a IPL/BBL treatment, some darker pigment comes to the surface and over the next several weeks, sloughs off. Sometimes the pigment brought to the surface is not obvious and the skin can gave a grey-bluish hue. The reaction also depends on the patient's skin type, medications, sun exposure, hormones and much more. If it is a a patient's first time getting a photofacial the provider may play it safe and have the laser settings initially lower until he/she knows how a patient's skin will react. That is a good thing because laser strength can be increased but it can be harder to "undo" laser treatments that are too strong. If a patient's skin did not seem to have any reaction or pigment surface, make sure to tell the provider so that the machine can be adjusted specifically for you.
As a patient, make sure you observe and remember exactly how your skin reacted the first two weeks after your treatment. That way, the provider will know if a setting adjustment is needed. It takes at least 3, usually 4 treatments to see the best results from IPL/BBL treatments. Be patient and consistent and ask your provider to take photos each visit so that you can see skin improvement over time.
Just looking at your photograph I do believe there probably is an effect of the IPL evident.
The day after IPL we do not see a very dark black appearance of the pigment. Usually it simply has a grayish or bluish hue and is not terribly darker.
You should begin to see the pigment come to the surface and look much darker most likely between 4 and 6 weeks. Typically 3 treatments are needed a month apart for maximum effect.