It's important that you abstain from any psychedelic use until you can get to your guided session.
Psychosis can happen. Overconfident guides can lead you there. Make sure you're working with someone who knows that there are risks.
Do you have any advice on how to procure a suitable guide? Ideally I'd want someone who's an experienced psychotherapist.
If things have never gone wrong for them, then they're not that experienced.
Find out if this is someone who takes responsibility for their actions.