I read the instruction manual on Auber's website. Since my SSRs are coming from them I think I will go with their recommendations.
"6.7 Cycle time “t”
Parameter T can be set between 0.5 to 125 seconds (t=0 represent 0.5 second). It represents the speed at which the output is turned on and off. When the output device is a mechanical relay, the cycle time should be set >4 second. To increase the service lifetime, it is recommended to set it between 20.0~60.0 seconds. However, longer time might reduce the accuracy of the control in a fast responding system. When the output is logic level that controls a SSR, the cycle time can be set at 2 seconds or less for better performance"
So, from reading this it sounds as though my Period needs to be two seconds.
The Zero Width could be 0.2 seconds and the Pulse(or Max) Width could be 1.8 Seconds. So for every 2 seconds that pass the SSR will be enabled for 1.8 sec at 100% command. At 0% the SSR will be enabled for .2 sec out of every 2 seconds. If by leading you mean "on" first, then yes it it a leading PWM. There will be a PID driving this PWM. The controller is a Honeywell Plant Controller.
Here is a pic of how they define PWM
Sorry the pic stinks.