What does 日にち会うかな？ means in the excerpts below?

1:

太巻きのお題は来年にしようかな？
日にち会うかな？
まぁ今年は、太巻きは買ってきて、豚汁作って食べますか。

2:

A: テニスやろ
B: みんな日にち会うかな？(^^;)笑

3:

それ見たいんだけど日にち会うかな…_|￣|○

4:

2日に帰る予定だから、日にち会うかな？

Despite my efforts I have failed to grasp a meaning that would fit all cases. My guesses so far:

• Maybe 会う should actually be 合う?
• 3 seems to imply "Sorry I can't go", while 4 sounds optimistic.