If Last Click gives all the credit and payout to the final partner to drive a click in the conversion path, First Click gives it to the first partner to drive a click in the path. This is considered less popular by partners and is generally not recommended.
With the First Click credit policy, the partner that drove the first click in the conversion path will receive 100% of the credit, and usually all of the payout for the conversion. However, receiving full credit may be dependent on your participation bonus setup.
A major difference between the First Click policy and the others is the need to set a lookback window. This window sets how far back impact.com should look for the first click in the conversion path. Since the conversion path is submitted when the action locking window starts (i.e., when a conversion, like a sale, is tracked), the lookback window determines how far back impact.com should look for the introducing partner.
For example, a lookback window set for 90 days will only look 90 days back from the time of the conversion. The partner that drove the earliest click in that window will win credit for the conversion even if the true conversion path took longer than 90 days.
Let's come back to The Roadrunner's DTC online paint store. They've decided to upgrade to the Professional edition for a handful of different reasons, and specifically want to switch over to the First Click credit policy as their crediting logic.
The Roadrunner decides on a lookback window of 45 days as all conversion paths took that long to convert when they were running Last Click. They also decide to prioritize the First Click policy over Last Click. Finally, all partners will be credited according to the First Click credit policy.
Somehow, their conversion paths look exactly the same as when they were using Last Click though. The customer always adds paint brushes through the home improvement blog's banner ad, add tarps after clicking on the sponsored search result, and make the purchase after clicking through the sponsored Instagram post. Since the switch, however, the home improvement blog has been winning all conversions since they drove the first click in the conversion path.
How do I request this credit policy?
Reach out to your CSM (or contact support) to discuss enabling the First Click credit policy. You'll want to share why you want to use this policy, if all your partners will be on First Click (and if not, which policy should take priority in a journey if more than one policy is present), and if you had a lookback window in mind.