She looks great now, man.
When to flip the switch is a judgement call, but from my experience, it's much better to flip it too soon than too late. There's nothing worse than having a plant in flower outgrow her box, because as a grower you're helpless to correct it at that point.
The best solution, imho, is to flip it sooner rather than later. If at the end of your grow, you see that your plant could've been a few inches bigger because there was still room in your cabinet, you'll know that during your next grow, you can probably let it veg for longer than you vegged this one. Does that make sense?
All that said, most strains/phenotypes behave differently, so this plant might not be a 'stretcher' but your next one might. Keeping the plants on the slightly smaller side allows to you keep in control of your grow, and means you have a slightly faster turnaround with your grows because you're vegging for less time than you had originally planned.
As for tucking above or under the screen, that's up to you as well. I only tuck under, not over and under, and I only usually tie the main top down to the screen because the stem is at it's thickest point and usually needs to be anchored to something to keep it in place below the screen. I suspect if your plant looks like it might stretch more than you had planned, tucking over and under the screen will shrink the final total height of your plant by a couple inches more than if you had just tucked under the screen (you're using more of the stem to go over and under than just under).
I keep tucking the main top until all the other side growth reaches the screen. Once all the 'side tops' are at the same level as the main top, I usually let them all grow through the screen at that point. All the tops that have made it to the screen ideally should grow another 3-5 inches above the screen and hopefully stop stretching at that point. What you're left with is 10-20 main tops, all about 5 inches high through the screen at a consistent height and evenly spaced out.
I hope all that makes sense.
Jim