Before the first spin, the bonus stays hidden
Choose your stake knowing that nobody can predict when the bonus round will land. How often it comes is not known in advance, and the result of one session is random whatever the RTP. RTP describes the return averaged over a very large number of spins, so it cannot tell you what your own session will pay.
Open the game rules before you play, because the RTP version running on Santa's Wonderland is shown only there. Read that line first, then set your stake. The version named in the rules is the one behind every spin you make in that game.
Treat the maximum win as a ceiling, not a target, since Santa's Wonderland reaches it very rarely. Set your session budget before the first spin and keep it. Any single spin can end with a small return or none at all.