How Can I Hold Off an Assertion Until Sync is Established Using a Local Variable?

In reply to hal9e3:

OK, solved this but had to go outside SVA to do it:

bit start_asserts;

always @(posedge clk) begin
	if (rst !== 1) begin
		#1 start_asserts <= 0;
		end
	else if ((d == SYNC_DATA) & !available) begin
		#1 start_asserts <= 1;
		end
	else begin
		#1 start_asserts <= start_asserts;;
		end
	end

property data_parity_prop (clk, rst, d, available, parity, start_asserts);
	@(posedge clk) disable iff (rst !== 1)
		start_asserts |-> (^d ^ available ^ parity);
	endproperty

Not pretty or elegant but it works.