My teacher told me it is dangerous to make it the BOS date. If you finish early it allows time to cope with a disaster such as breakage, loss or it didn't work out. Consider it a type of just in case protection.
The teacher has had cases where students work was smashed accidentally, or blew up in the kiln etc. Finish on the due date there is not ime to rectify a mistake. You could end up sending your VAPD instead