As far as I can tell Jiva Beach is busy from April to October so is always at or close to full capacity. We were there in October and also last month and both times equally busy. The only difference between the two was that the beach bar wasn't open in April but the weather had been relatively poor in the week prior to us arriving. They were setting it up while we were there.
October was very busy - we have Scottish school holidays then English so a busy month. All facilities open.
We haven't experienced pushing or over busy buffets - there's often a queue of 3 or 4 for the omelette station but the buffet is very large so no part is ever frantic.