Hi, Within one week after the release of the results, i.e. around Christmas or after boxing day perhaps.
They're normally there the Monday afternoon after the results come out. Theoretically the solutions could be released after the exam diet is finished but I guess they want to incorporate the Examiners' comments which probably aren't finalised until just before the results are published.
The solutions will also be changed in light of actual student responses. Even in mathematical papers in cases where the most common approach was not anticipated by the question writer.