Almost all players will send entry on the last day in this way competitors will not make efforts to defeat other users competitors can only guess
It will be different if the entry is sent via PM they don't know each other except the contest manager.
As we know, if the entry is submitted publicly most participants will submit it in the last hours even minutes.
There are some submission already but do not even think that those are the final entry from the participants.
The most important thing for this kind of contest is, try our best and do not try to think about other's submission as it may force us to play more and more in order to get better entry but it can make us lose more than what was planned.
If I am with the contest manager, I will make a unique rule that players should post their entries as soon as possible or they can also lessen the duration of the contest because it does not make sense if most of the participants are only going to post their entries on the last minute. If we don't want to lose big then we can avoid contests like this.