I want to verify if 行ってもいい is the correct term, or if another word(s) can be used.
One idiomatic way of saying "good to go" is
準備 (also 用意) means "preparations".
Another standard way would be
行ってもいい could be misunderstood as asking "may I go?". 行く may indeed be used in this context for "are you good/ready to go?" as 「（もう）行けますか」. However, I don't think 「行ってもいいです（よ）」 would be a natural way of saying "I'm good to go".