Agrigento to Syracusa public transit

Hello Everyone,
My husband and I plan to travel from Agrigento to Syracusa in mid April by public transit.
I see that there's a 4hr 5m bus trip from Agrigento consisting of: 2hr 40m to Catania, followed by a 30m transfer, followed by a 55m bus Catania to Syracusa.
My questions: do these buses usually sell out in mid-April? And also, in case the first bus is delayed, should we consider booking 2 separate buses with a longer transfer time?
Thanks in advance for any info and tips. We will not be traveling on a Sunday!