Transfers and Stayman are only on over auctions where the NT bid is the first natural bid by the partnership. The three common auctions where Stayman and transfers are used:

1) 1NT (15-17)
2) 2NT (20-21)
3) 2C-2D* *Notice how the 2C and 2D are an artificial platform to get to 2NT.
2NT(22-24)

When the partnership has had a natural auction that gets to either 1NT or 2NT then transfers and Stayman are OFF. The two most common examples of these auctions are:

4) 1C-1H
1NT
5) 1D-1S
2NT

In both of these auctions the Opener and Responder have bid naturally. In the first auction the Opener showed 12-14 HCP, and in the second auction the Opener showed 18-19HCP (the scenario that you directly asked about which we will now go over).

NOTE: Notice that the five examples above are the entire methodology of how Opener handles any hand that is balanced and has from 12-24 HCP

RESPONDERS REBID AFTER OPENER REBIDS 2NT

The first rule in this auction is that in standard all bids by Responder are forcing.
• Responder can rebid their major to show 6 cards or longer in their major
• Responder can rebid the other major to show 4+ cards in that suit
• Responder can bid 3NT to end the auction
• Responder can make a quantitative invite by bidding 4NT
• Responder can bid partner’s major to create a force and look for the best game or slam.
• Responder can bid the other minor (artificially) which allows the Opener to show 3-card support for the major.

An example of these rules:
1C- 1S
2NT- 3C: Natural and Forcing
3D: Artificial and asking if partner has 3-card support for spades
3H:: Natural. Four or more hearts and five or more spades
3S: Natural. Six or more spades
3NT: To Play
4C: Gerber
4H: Choice of games. At least 5/5 in the major.
4S: To Play.
4NT: Quantitative.

Thanks,
Corey

I think here is a typo. Probably:
1H 1S
2D 2H
3D

This is my first experience working with the blog. I have worked on some of the ideas that I want to express, but the mechanics of posting/subscribing, etc are very new to me.