Should gravity change at all during 'lag time'?

I am aware that it could take 72 hours to show visible signs of fermentation ( https://www.homebrewtalk.com/f39/fermentation-can-take-24-72-hrs-show-visible-signs-43635/ )

I got impatient after ~60 hours of no visible activity of any kind, so I took a gravity reading. It looks like it hasn't changed at all (I got 1.126. My original reading, 1.113, was inaccurate estimated because I forgot to take the temperature, but it could be as high as 1.129).

I'm using Montrachet yeast. This is basically a pineapple wine with ginger. I thoroughly aerated before adding the rehydrated yeast. The temperature of the mix was hot but drinkable, which puts it lower than 140F for sure, probably lower but I have no way to know how much. I'm a little worried in my rush I may have killed the yeast.

According to http://winemaking.jackkeller.net/strains.asp , Montrachet doesn't do well at high brix. Well, this is already ~0.016 gravity higher than I intended.

What should I do now? I have about half a packet of dry Pasteur Champagne yeast I could sprinkle in... Or I could go buy more yeast. Since I'm over my intended sugar target, a stronger yeast strain might be preferred...

Or should I keep waiting even as the 72 hour mark is approaching? My main concern is that since there are no preservatives, the pineapple juice might go bad.

140F is very hot and there is a good chance the yeast is dead. Wine yeast is cheap, so buy some more and pitch it.

I was thinking 140F was probably a highball, but I just looked at a hydrometer correction applet, and at 130F it would make 1.113->1.126, so looks like you're right

Dead yeast would explain all the sediment at the bottom (there's a fair bit of it...) should I try and filter that out or could that be beneficial?

Also, should I re-boil all the ingredients since it has been 3 days and there aren't preservatives in there?