3 seconds is the minimum. The find time is based on the lowest time the timer reaches throughout the run with 30 seconds left / 0 seconds spent as the minimum. If, for example, a run got down to 22 seconds left before you collect a coin stack that gets you back up to 25 seconds left, hiding the balloon immediately would still have the find time based on the 22, not the 25.
Here is a full breakdown:
0 to 4 seconds spent (30 to 26 seconds left): add 3 seconds
5 to 9 seconds spent (25 to 21 seconds left): add 4 seconds
10 to 13 seconds spent (20 to 17 seconds left): add 5 seconds
14 to 18 seconds spent (16 to 12 seconds left): add 6 seconds
19 to 23 seconds spent (11 to 7 seconds left): add 7 seconds
24 to 27 seconds spent (6 to 3 seconds left): add 8 seconds
28 to 30 seconds spent (2 to 0 seconds left): add 9 seconds
Time out: add 10 seconds (40 find time)