Help with quickest, earliest transport. to Tirano from Vareena

If you mean the town on Lake Como the reason you can't find it is because spelling counts on the railway websites. The town is Varenna. I don't know of any place called Vareena.

The train station is called Varenna-Esino. It takes 1:28 and leaves at xx:24. You didn't quote a date so randomly choosing April 15 the first one is at 07:24 arriving Tirano 08:52.

You could presumably hire a taxi for an earlier trip but be prepared to pay for the driver to drive both ways.

And here is the schedule for the Bernina Express:

https://www.rhb.ch/fileadmin/user_upload/redaktion/Home_Marketing/Panoramazuege/Bernina_Express/Fahrplaene/BEX_Fahrplan_de_en_it_fr_WEB.pdf

It departs Tirano at 10:07 and arrives in St. Moritz around 12:36. The train Nigel mentioned from Varenna will get you to Tirano in time for this train. But I don't know if that is in time to catch the Glacier Express.

You might do better with regional trains which run more frequently than the named special trains.

Try spelling it Varenna. The actual station name Varenna-Esino.
I think I gave you that info already on your other thread, 7.24 am. Can't make the Glacier Express.
Use www.sbb.ch/en.

Now here is a way you can make the Glacier Express. Take a train at Varenna-Esino going toward Milan at 5:37 am. Get off at Monza at 6:27 am and get a train to Bellizona at 6:53 am, arriving at Bellinzona at 8:37 am, Outside the station, take the Postbus going to Chur at 8:45 am (reservation required), get off at Thusis at 10:20 am, then to the train station across the street and get a local train to Tiefencastel at 10:30 am, arriving at 10:46 am. The Glacier Express will arrive at 11:33 am going the opposite direction, so you will have to use the under track passageway to get to it. You'll arrive at Brig at 6:40 pm.

There is a train to Spiez at 6:48 pm, but you probably will not be able to make it, as the Glacier Express actually drops you outside the main Brig station in the street (believe it or not). You' ll have to cross the street to get to the station, then to the right platform. There is another train at 7:20 pm to Spiez connecting to trains to Interlaken Ost, then Lauterbrunnen, then Wengen, getting you there by 9:19 pm.

PS. since you have 45 minutes to kill in Tiefencastel, as an alternative, stay on the train until the next stop at Filisur. That way, you will ride over the famous Landwasser Viaduct, the one in all the Glacier Express posters. You'll get to Filisur at 11:00 am, and the Glacier Express arrives at 11:19 am and you'll get to ride over the viaduct a second time in the opposite direction.

Riding over the viaduct from Tiefencastel on a regular train where you can open the windows and get a clear view.
https://www.youtube.com/watch?v=2IR0jqy7YnE

Thank-you to everyone for your help and suggestions! So we probably need to re-vamp our plans/schedule & just do one
Scenic train. And thank-you for the "spell check"... VARENNA.

Might there be a bus (regional transport.) to Varenna to catch the Glacier Express. If you had to choose one Panoramic
train, which one would you choose???

I would choose the Bernina Express (or a regional train on the same tracks, with the same scenery) hands down. We have spent a lot of time in Switzerland ( 5 trips) and that train is quite nice.

I recall several times standing on platform in Betten, a small station on the Glacier Express route, but not a stop on the panoramic named train. This is in the steep area where the train proceeds slowly, so we could see the passengers as they passed by. Everyone looks bored.

As I understand it, your final destination is Lauterbrunnen or somewhere in the Berner Oberland? If you confirm that, people here can help you figure out a route that makes sense from Varenna, starting with a train over the Bernina Pass, but not necessarily the named Bernina Express.