It of course depends if you are the chair or a councillor. The chair can call an EO meeting at any time and if councillors feel there is a need then the chair can call one on request. if they refuse the request then the legislation states: " If the Chair refuses to call an extra ordinary meeting of the council after a requisition for that purpose. signed by two members of the council, has been presented to him, or if, without so refusing, the chair does not call an extra ordinary meeting within seven days after which such a requisition has been presented to him, any two members of the council, on that refusal or on the expiration of those seven days, as the case may be, may forthwith convene an extra ordinary meeting of the council"
Don't for get that the number of days notice that apply to normal PC meetings apply to EO meetings