Thanks to all for your excellent feedback on this post. As a result I have come to a different understanding and am abandoning the temporal view I was investigating. "Since" is too unlikely with "coming".
If you are interested, what I think I see now is that the 144,000 represent those killed in the persecution during the "last hour" prior to
the great tribulation, not the tribulation itself:
[Mat 24:9-13 NLT] (9) "Then you will be arrested, persecuted, and killed. You will be hated all over the world because you are my followers. (10) And many will turn away from me and betray and hate each other. (11) And many false prophets will appear and will deceive many people. (12) Sin will be rampant everywhere, and the love of many will grow cold. (13) But the one who endures to the end will be saved.
[1Jo 2:18 NLT] (18) Dear children, the last hour is here. You have heard that the Antichrist is coming, and already many such antichrists have appeared. From this we know that the last hour has come.
The second group are those coming out of the great tribulation, presumably through death:
[Mat 24:15-22 NLT] (15) "The day is coming when you will see what Daniel the prophet spoke about--the sacrilegious object that causes desecration standing in the Holy Place." (Reader, pay attention!) (16) "Then those in Judea must flee to the hills. (17) A person out on the deck of a roof must not go down into the house to pack. (18) A person out in the field must not return even to get a coat. (19) How terrible it will be for pregnant women and for nursing mothers in those days. (20) And pray that your flight will not be in winter or on the Sabbath. (21) For there will be greater anguish than at any time since the world began. And it will never be so great again. (22) In fact, unless that time of calamity is shortened, not a single person will survive. But it will be shortened for the sake of God's chosen ones.
These are not martyrs but they are indeed saints.
My view is obviously still a work in progress.
Thanks again for the help.
What I lack in youth I make up for in immaturity.