Five-day gap
In some cases, the zygote keeps growing well after the two-cell stage. Additionally, twinning might not start until day 5. These kinds of twins are referred to as mirror image twins with individual placental sacs.
It makes sense that this form of the split will result in twins with less variety in their DNA compared to those from a two-cell split.
The majority of twins are born between the third and seventh days after conception.