What de-acceleration rate does the spoilers have? If it exceeds AB1 the A/B's don't engage until the de-acceleration rate slows to the AB1 rate.
Full thrust reversers and spoilers de-acceleration rate is approx. 2.75 at touchdown and decreases to approx. 2 around 100kts. That's how come, with AB2 selected, you don't feel them engage until below approx. 100kts if you're using full thrust reversers.
Someone mentioned keeping thrust reversers deployed until exiting the runway. The manufacturers have specific guidance for various engine/airframe combinations. It's often 'stowed by 60' or 'coming out around 60 to be stowed prior to taxi speed'. I'd go with the official recommendation.
Carbon brakes can be touchy but they can be smoothly manipulated. Early 767-200's were terrible and early 757's have that brake metering sponginess issue at low brake pressure.
The slower you are when you try to disengage the A/B's the bigger the lurch will be. Because of that I typically try to disconnect them around 100 kts(AB2 hasn't activated, AB3 is at approx. 1/3 rate- de-acceleration 2 is from spoilers/thrust reverser).