10 Min (Dolmens Timer) - Help Request

[Luxor]

So after three days of learning how to use lua and xml, I'm still very much lost when it comes to actually creating something of my own.

What I'm trying to do is create a 10min timer (doesn't matter whether its counting up or down). I'm currently working with seconds as minutes seem a bit complicated as I think i'd have to display the active conversion of minutes from seconds, which itself is already out of my present abilities.

At the moment, I have a functional counter synced to GetFrameDeltaTimeSeconds() every time my addon updates however, GetFrameDeltaTimeSeconds() seems to be 3x the speed of actual seconds on a clock. It's still better than updating every frame but it still isn't what I want it to be.
My current codes are:

Timer.lua

local counter = 0
local delta = GetFrameDeltaTimeSeconds()
 
function TimerUpdate()
    TimerCounter:SetText(string.format("Timer: %0.2fs", counter))
    counter = counter + delta
end
 
function TimerInitalized()
end

Timer.xml

<GuiXml>
    <Controls>
        <TopLevelControl name="Timer">
            <Dimensions x="200" y="42" />
            <Anchor point="CENTER" />
 
            <OnUpdate>
                TimerUpdate()
            </OnUpdate>
 
            <OnInitialized>
                TimerInitialized()
            </OnInitialized>
 
            <Controls>
                <Backdrop name="$(parent)BG" inherits="ZO_ThinBackdrop" />
                <Label name="$(parent)Counter" font="ZoFontWindowTitle" color="CFDCBD" wrapMode="ELLIPSIS" verticalAlignment="CENTER" text="Timer: ">
                    <AnchorFill />
                </Label>
            </Controls>
        </TopLevelControl>
    </Controls>
</GuiXml>

Also I wouldn't even know how to get it to stop once it reached 600secs (10 mins).

In pure Lua it would look something like this:

function sleep(s)
  local atime = os.time() + s
  repeat until os.time() > atime
end
 
Time = 0
 
for i=Time, 599 do
    print (i + 1)
    sleep(1)
end

However, I don't know how to even implement something like that into ESO.

All help is appreciated.

Thanks in advance!