How to Cycle a new breeding tank

Dear fellow fishkeepers,

After 2 years of not keeping any discus, I decided to dive back in. And this time straight to getting a breeding pair and have a first time go at breeding.

I picked up a second hand Juwel Lido 120 that i cleaned and now sits empty. I normally would cycle the tank with some tetras or guppies or whatsoever, but since this will be a breeding tank, im not sure how to cycle as the only fish I want in there are going to be the 2 discus.

Now, the backwall of the tank had some algae on it and it had some red shrimps in it before. I think i have gotten all the shrips out (but 1 or 2 may have been left behind in a crevice and are now dead) and the since the tank has been dry for about 2 days, im assuming the algae is mostly dead. Furthermore, I have not cleaned the filter media, but it is in a bag and mostly dried up, so i assuming the bacteria are mostly dead, but it still has the mulm on it.

If i would fill up the tank again, would the waste from the dead algae, possibly a dead tiny shrimp or 2 and the mulm on the media be enough to start a cycle before I put the discus in?

And how long should i cycle it for then?

Any help is greatly appreciated as this will be a costly pair of fish and i do not want them to get hurt or even worse, die!