Just write a second date (maybe 11 or 12th of July?) , if they don't show up, it'll be a walkover and huj v dupe.
It's almost July and pretty cool kinda of weader will be so I want to know the date because I won't waste time for waiting if the opponent shows up or not. This time it's our turn to not show up vs them - if the weader is awesome, I'll put fat long huj on the game and go drink at the lakes. By this reason someone might hawe to assign third date.