In early 1701, Louis registered Philip's claim to the French throne with the Paris Parlement, raising the possibility of union with Spain, contrary to Charles' will. In February, the Spanish-controlled Duchies of Milan and Mantua in Northern Italy announced their support for Philip and accepted French troops. Combined with efforts to build an alliance between France and Imperial German states in Swabia and Franconia, these were challenges Leopold could not ignore. At the same time, French garrisons took over Dutch-held 'Barrier' fortresses in the Spanish Netherlands, helped by the Spanish Viceroy and French ally Max Emanuel of Bavaria. This undid Dutch gains made at Ryswick and threatened their lucrative monopoly over the Scheldt granted by the 1648 Peace of Münster. It was also a concern to English merchants since control of the ports of Antwerp and Ostend would allow France to blockade the Channel at will. In response, Leopold, the Dutch Republic and Britain signed the Treaty of The Hague on 7 September 1701 renewing the 1689 Grand Alliance. Provisions included securing the Dutch Barrier in the Spanish Netherlands, the Protestant succession in England and Scotland and an independent Spain but made no reference to placing Archduke Charles on the Spanish throne. When the Stuart exile James II died on 16 September, Louis reneged on his commitment at Ryswick to recognise William as King by proclaiming James Francis Edward King of England and Scotland. The vast majority in Britain now supported war and after William's death on 19 March 1702, Queen Anne announced the continuation of his policies ie ensuring the Protestant succession and resisting French expansion. The Dutch did the same and on 15 May the Grand Alliance declared war on France, followed by the Imperial Diet on 30 September.
Question: How many months after the Grand Alliance declared war on France did the Imperial Diet follow?
Answer: 4