According to the Mahabharata, when Sisupala was born with three eyes and four hands, it was proclaimed that the person who caused them to disappear would be Sisupala's slayer. Since his mother Shrutashravas was Krsna's aunt, Krsna and Balarama too came to see their cousin. But as soon as Krsna placed Sisupala on his lap, the third eye and extra two hands disappeared. This must have happened when Krsna was twelve years or older.
Now later on, (in Srimad Bhagavatam), after constructing Dvaraka, Krsna marries Rukmini, who was betrothed to Sisupala. Here, unless the seventeen battles of Jarasandha took more than a decade, Sisupala couldn't have been more than ten years old. How then could he marry Rukmini? And if Rukmini was younger than Sisupala what was the age gap between Krsna and Rukmini?
To summarize: How older was Krsna to Rukmini and Sisupala and at what age did her marry Rukmini?