Referral Program That's Actually Working for My Custom Cabinet Jobs

I've been running a simple referral setup for my carpentry side hustle, where I give folks a $50 Home Depot gift card for every new client they send my way who books a job over four hours. It's mostly for built-in shelving and custom trim work, and honestly, it's turned a couple of repeat customers into my best marketers without me chasing leads. I keep track of it all in a basic Google Sheet, nothing fancy, but it weeds out the tire-kickers real quick. Last month, it brought in three solid gigs for kitchen remodels, and the word-of-mouth feels more genuine than any ad I've tried. The gift cards don't break the bank, and clients love the perk since they're always needing more supplies anyway. Anyone else using something similar for their woodworking projects? Saw a thread on r/woodworking about tying perks to specific tools, but I kept it simple with the card.