How long does a player have to be on the pitch to count as an appearance?

[HeavensAAA]

Start him at the beginning and sub him straight away. Guarantees an appearance

Most of the time, except if the player gets injured in the first few minutes before he could be substituted (if not substituted early, the player has to stay uninjured for the first 20/30 mins to be counted as 1 appearance - also cannot remember clearly if it is 20 or 30)