There are many commentaries on line about Varys movement. Mostly, the theme is there has definitely been a passage of time to allow Varys to get back and it is further exemplified by the dragon heads on the ships, the Dornish ships in the armada and the very real but unseen need for Dany to make sure that everything is okay in Mereen before she leaves. There had to be some rebuilding and political stabilization of the area before she left the Bay of Dragons, previously known as Slaver's Bay. One supposes that there could have been some mention of the passage of time, (calendar pages flipping by like films from the 40's) or a scroll anouncing the passage of time, like Desparate Housewives of Westeros. Still time had to pass for Varys to get to Dorne, Oleanna to get from HighGarden to Dorne and the Sand Sisters to restock their poison.