I Have done it both ways with my VG 540 Truevis, I have not seen a problem yet, I normally wait a day before laminating but if the vehicle is at the shop and you mess a piece up you need to make it right away, I usually try to wait 2 hrs, then laminate.
I also have not experienced the "white" vinyl problem when stretching, I even heated some and stretched it to try to duplicate this and haven't seen it.
The prints come off the Truevis dry and VERY scratch resistant, with my old VP 540, if I sneezed on a banner before a 24 hr dry time it would scuff, (which in turn has made me a sharpie repair pro" if I didn't wait a day to hem I would mark it all up. Not so with my VG 540, I wait maybe 1 hr and flip the banner over and hem it, never marked them up at all, on the old VP I marked a lot of prints up just getting them rolled up after printing or on the table, not any more they are mostly dry by the time they hit the floor or the take up.
I also noticed the solid colors look exactly the same as cut vinyl, on my VP the greens were grainy (among many other colors) and the cutting is more accurate, one trick is you have to remove the roll of vinyl behind the machine when cutting a laminated print, and you have to slide the roll holders out of the way, the machine is so fast and strong the print can smack the roll holders back there and get knocked off it's marks.
The VG is the machine I thought I was getting when I bought my VP.
Also maintenance is way easier and faster, most of the ink is on the cap tops, you gotta keep them clean, the heads usually have very little ink on them,
AND make sure you use the media clamps, they are only the long ones with the VG and a lot of guys skip using them, you gotta remove them to cut off your media (machine senses if you have them on and warns you, no more cutter crash with the media clamps LOL) and it's easy to forget to put them back on, hence the never ending posts of "had to replace a zillion heads on my VG"
The True Vis is slightly different than the older printers, it takes a little to get used to it, once you get it down, it's all skate time.
I just printed a HUGE wall wrap for a local college, the color consistency from panel to panel was amazing, like the thing was screen printed no variations in the panels, this wrap was designed by a top notch designer and he is overseeing the job, he is so picky "but fair" I would never have gotten past him with my VP