Rescission ab initio means that contract was void from the very beginning and therefore parties are to be restored to the same position they were before the contract was made. Since no contract ever came into existence no one can claim damages under it.
Per Lord Blackburn in Dahl v Nelson, Donkin, and Others, (1881) 6 App. Cas. 38 at 54:
A considerable argument ensued, [council for the charterers] contending then, as he did afterwards, that the prevention must be physical, from something endangering the safety of ship, and that it must be permanent; and when pressed he said that though the cause obstruction was a physical one and one which would last a year, the steamer must wait a year. The Master of the Rolls [Lord Hershell, in the Court of Appeal] said, as I think he well might, "To suppose that two commercial men should enter into a contract to charter a steamer to go to a dock, or as near thereto as she might safely get, that that means that she is to wait outside for a year because the dock is out of repair, is to my mind absurd."
I do not pretend to lay down any precise rule as to what is reasonable what is not. I think the main elements to be considered are, what would be the effect on the object of the contract; and the damage to each party caused by the delay; and if the result be lead those who have to decide the question to think (to adopt the language of the Master of Rolls) that it is absurd to suppose that two commercial men entering into a contract to charter a steamer to go to a dock, or as near thereto as she may safely get, should mean that she was wait outside so long, they ought to find it unreasonable.
Per Lord Watson in Hick v Raymond  AC 22 at p.32:
When the language of the contract does not expressly, or by necessary implication, fix any time for the performance of a contractual obligation, the law implied that it shall be performed within a reasonable time. The rule is of general application, and is not confined to contracts for the carriage of goods by sea. In the case of other contracts the condition of reasonable time has been frequently interpreted; and has invariably been held to mean that the party upon whom it is incumbent duly fulfils his obligations notwithstanding protracted delay, so long as such delay is attributable to causes beyond his control, and he has neither acted negligently nor unreasonably.
Mr. Justice Scrutton said in Embiricos v Sydney Reid & Co.,  3 K.B. 45, at p. 54:
Commercial men must not be asked to wait till the end of a long delay to find out from what in fact happens whether they are bound by a contract or not; they must be entitled to act on reasonable commercial probabilities at the time when they are called upon to make up their minds.