Lua How do I create delay time between each 'try' to magic wall?

[Ond||Apokalypse]

(8.0 exe evolution)

local storevalue = 9079 -- value where exhausted is saved
local exhausttime = 0.3 -- 0.3 seconds exhaustion

local combat = createCombatObject()
setCombatParam(combat, COMBAT_PARAM_DISTANCEEFFECT, CONST_ANI_ENERGY)
setCombatParam(combat, COMBAT_PARAM_CREATEITEM, 1497)

function onCastSpell(cid, var)

    if(exhaust(cid, storevalue, exhausttime) == 1) then
    return doCombat(cid, combat, var)
    else
    doPlayerSendCancel(cid, "You are exhausted.")   
    end
end

I'm not talking about exhaust - Delay time if you 'poffed' a magic wall on a player (didn't succeed to place it)
Delay time between those tries