A debate that sometimes crops up in Reformed circles is whether the elect are justified from eternity. That's not a yes or no question. Because justification involves a relation between a divine act and the resultant state, any answer is equivocal unless we distinguish both sides of the transaction.
In one respect, justification is a divine act. If God subsists outside of time, then justification is timeless or eternal in that regard.
Conversely, justification is the result of a divine act. When that takes effect is a separate question. A timeless divine act can be effected in time, at different times.
So in another respect, justification is the state of being justified. Although God is timeless, humans are timebound. The elect are justified in time, and that's contingent on faith in Christ. God doesn't decree justification in isolation; rather, he decrees justifying faith in tandem with the decreed result.