J. I Packer, A Quest for Godliness: The Puritan Vision of the Christian Life, p. 155.

The final element in the Puritan development of the doctrine of justification was to safeguard it against mis-statement within the Puritan camp. Chapter XI of the Westminster Confession wards off two such abberations. The first is that justification is from eternity, i.e., before faith. William Twisse, first prolocutor of the Assembly, had maintained this as part of his case against Arminianism, but in addition to being unscriptural the idea is pastorally disastrous, for it reduced justifying faith to discovering that one is justified already, and so sets seekers waiting on God for assurance instead of exerting active trust in Christ. The trouble here was the assimilating of justification to election, and the Confession deals with it by drawing the correct distinction; “God did, from all eternity, decree to justify the elect… nevertheless they are not justified until the Holy Spirit doth in due time actually apply Christ unto them” (XI:iv).

I read this some time in the early nineties.  Before seminary.  Maybe while living in Nashville but probably even earlier in Florida before I got married.