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Since your tank has only been set up 3 days, it's far too early to be thinking of fish additions. A cycle can take anywhere from 3-8 weeks depending on the set up.
Since this will be an FOWLR
, will you be using cured or uncured LR
If cured you can read >>here
<< about fishless cycling. If >>uncured LR
<<, then the die off from the rock should produce a sufficient ammonia spike to initiate the cycle process.