Stable one vs challenges one which one to choose.

Recently, I interviewed with a company that is in its growth phase. They are asking me to build one of their apps (I have similar experience and am confident I can scale it). My current job is stable, but current company is planning to go for an IPO within the next two years. The question is whether I should switch now, build something impactful along with a good compensation package, or wait until the next appraisal cycle in July. The current offer includes a hike of around 50–55%, which I am unlikely to get in my current company for at least another year. Kindly suggest.