The most common way a new supplier relationship goes wrong isn't a bad first job — it's skipping questions before the first RFQ that turn into problems on the third or fourth one. A quick, consistent onboarding pass catches most of it up front, before you've got a job on their floor.
Before the first RFQ
Capabilities, verified, not assumed. A supplier's website says what they'd like to be known for, not necessarily their actual day-to-day capability. Ask directly: what processes, what tolerances they hold reliably, what materials they run regularly versus occasionally. A supplier who "can do" tight tolerances as an occasional stretch is a different bet than one for whom it's standard work.
Capacity and typical lead time, separate from what they'll quote on a specific RFQ. A supplier under-capacity might quote an optimistic lead time to win the job, then struggle to hit it once it's real. Asking about typical, not best-case, turnaround gives you a more honest baseline to compare their actual performance against later.
Certifications and documentation they can actually provide — ISO status, material certs, first-article inspection reports — confirmed before you need them for a specific job, not discovered as a gap when a customer requirement depends on it.
Payment and commercial terms, agreed before the first invoice, not negotiated for the first time when it's already due. Net 30 vs. net 60 is a meaningfully different conversation before a relationship exists than after.
During the first few jobs
Start with something lower-stakes. A new supplier's first job with you shouldn't be your most schedule-critical or highest-volume order. Give them something you can absorb a miss on while you're still learning how they actually perform against what they said.
Track the actuals against what they quoted, from the first job — quoted lead time versus delivered, quoted price versus final invoice. This is exactly the data that turns into a real performance picture later, and it starts mattering from job one, not once you've decided they're a "regular."
Give specific feedback if something's off. A tolerance issue or a late delivery on job one is a normal thing to flag directly and specifically — it's far more useful to a new supplier (and to you) than quietly routing future RFQs away without ever saying why.
Making the checklist actually get used
A checklist that lives in someone's head doesn't survive turnover or a busy week — the questions that matter get skipped under time pressure exactly when they matter most. The value of a checklist like this comes from it being consistently applied, not from how thorough it looks the one time someone reads it carefully.
Once a supplier's onboarded, keeping their performance data in the same place as every other supplier is what makes "is this new vendor actually working out" an answerable question three months in, instead of a gut check. RFQTrace tracks response rate, quote accuracy, and delivery performance automatically from a supplier's first RFQ onward. Start a free 60-day pilot and build that record from day one with your next new supplier.