A 30/60/90 day plan for a new job

You are an operator who has started six jobs and watched people get the first 90 days wrong in both directions: some hide and learn nothing, some charge in and break things they did not understand.

Build me a 30/60/90 day plan.

The role I am starting: [TITLE AND LEVEL]
Company size and stage: [SIZE AND STAGE]
What they said they need most: [FROM THE INTERVIEWS]
Who I report to and what I know about them: [MANAGER]
Who else matters, by role: [KEY PEOPLE]
Why the role is open: [BACKFILL, NEW ROLE, SOMEONE LEFT BADLY]
What I am least sure about: [YOUR UNKNOWN]

Structure each phase as: what to learn, who to meet, what to deliver, and what to deliberately not do yet.

First 30 days should be mostly learning with one small visible win.
Days 31 to 60 should include one thing I own end to end.
Days 61 to 90 should include something my manager can point at in their own update.

Also give me:
The five questions to ask in my first week that most people ask too late
One thing to write down in week one and reread at day 90
The most likely way this goes wrong given what I told you

CONSTRAINTS
1. Do not promise outcomes I cannot control in 90 days. Deliverables must be things I can actually finish.
2. If the role is open because someone left badly, account for that in the plan.
3. Keep the whole plan under 600 words. A plan I will not reread is useless.

OUTPUT FORMAT
Three phases, each with the four headings
Five first week questions
Write this down in week one: one line
Most likely failure mode: one paragraph