You should take the signal for inc/dec speed from the suction pressure.

1. start the compressor unloaded at minimum speed

2. increase the solenoids for cap step by step

3.when compressor is in 100% on the solenoids start inc speed step by step.

reverse for decreasing cap.

This will save many start stop and give you a very smooth operation, plus at minimum cap the compressor load would be next to nothing.