The formula works if I compare exact days, but it's possible that the person filled out a form today and will only fill out the other the next day, so it's important to test for a couple of days ahead and behind anyway.
This is the working formula for the same day:
=if(INDEX(F:F,MATCH(1,(H:H=C3)*(DAY(LEFT(F:F,10))=DAY(LEFT(A3,10))),0))<>"","Yes","No")
This is my attempt to make it work for 1 and 2 days later:
=IF(OR(
if(INDEX(F:F,MATCH(1,(H:H=C3)*(DAY(LEFT(F:F,10))=DAY(LEFT(A3,10))),0))<>""),
if(INDEX(F:F,MATCH(1,(H:H=C3)*(DAY(LEFT(F:F,10))=DAY(LEFT(A3,10)) 1),0))<>""),
if(INDEX(F:F,MATCH(1,(H:H=C3)*(DAY(LEFT(F:F,10))=DAY(LEFT(A3,10)) 2),0))<>"")),
,"Yes","No")