when a contract states no time for performance the parties may perform at any time
This is not true because when this is the case, it must be performed within a reasonable time and not anytime. Specifically, if no time for performance is specified in the oral agreement for instance, then the performance may not exceed one year and this means that the statute of frauds would not apply.
In such a contract, in case the time for the performance is not stated in it, the it must be performed within a reasonable time. on the other hand, if the time is stated, then the court will allow some additional time for the performance unless something indicates that time is of the essence, then-time for performance will be strictly enforced. Before performance and following performance, condition may determine the rights and duties of the parties.