[Vlad]

A small rewrite, take what you wish from the code:

local addonName = ...

local function th(i)
	if i > 3 and i < 21 then
		return i .. "th"
	end
	local n = i % 10
	if n == 1 then
		return i .. "st"
	elseif n == 2 then
		return i .. "nd"
	elseif n == 3 then
		return i .. "rd"
	end
	return i .. "th"
end

local frame = CreateFrame("Frame")
frame:RegisterEvent("ADDON_LOADED")

frame:SetScript("OnEvent", function(self, event, ...)
	if event == "ADDON_LOADED" and ... == addonName then
		-- mySavedVar and charVar should be loaded now - but the names are too vague and other addons might overrite your values, if the other addons are badly coded.
		if type(charVar) ~= "number" then
			charVar = 0
		end
		charVar = charVar + 1
		if charVar == 1 then
			print("Hello " .. UnitName("player") .. ", it's nice to meet you!")
		else
			print("Hello again " .. UnitName("player") .. ", this is our " .. th(charVar) .. " meeting.")
		end
	end
end)