the impressario is at her tent in

Auridon outside Vulkhel Guard,
Stonefalls outside Davon's Watch,
Glenumbra outside Daggerfall,
Vvardenfell outside Vivec City,
Blackwood outside Leyawiin,
Northern Elsweyr outside Rimmen,
Summerset outside Alinor,
High isle outside Gonfalon Bay,
Craglorn near Belkarth on the Festival Grounds

there's a calendar symbol on the map where she is if i recall correctly