Two years ago was Senator Cruz's first year to nominate. No interviews. Just a letter out of the blue in mid-December. Senator Cruz later put out a press release, around 20 DEC, with all the different academy nominees listed.
Last year, Senator Cruz didn't do a press release. To my knowledge Senator Cornyn has not done one in the years I've been paying attention.
Just going on my experience from two years ago, you'll probably hear something from Senators Cruz and Cornyn early- to mid-December, before Christmas.
FYI, last year Senator Cornyn posted a picture of his nominating committee meeting in Austin. I think it was around the 20th, like your letter said for this year also.
Good luck, Texan.