Django: can I block new entries until one is completed?
Other approach is to write last win datetime right away in step 3, so 
3) If it's a winner again, create win record and give it (or other form) to user to fill the fields
As mentioned, after some time expiration you can check/remove empty win records
Sorry for the vague question, here's what's going on:
I will be giving away "win codes" to people. My django app is written so that the first one to enter a valid code XX hours after the last win will again be a winner.
If the user is a winner he will be redirected to a page with a form to claim his prize.
1) User enters code
2) I check the datetime of the last win
3) If it's a winner again, go to the form page
The problem is: if someone wins and then another person enters a code before the first one has filled in the form to claim the prize, the second one will get to that form as well because the last winner is still more than XX hours ago.
How can I avoid this? Can I somehow check if someone already made it to that form?