Travelling South

The junction immediately south of Luxembourg city where you turn off the E25/411 towards Metz tends to get congested at any time of year and the A31 between Metz and Nancy is slow (busy two-lane often with a 90km/h limit).

The route via Reims is usually less congested, make for a more relaxing drive, it is though considerably more expensive in tolls.

The approach to Dijon is the same either way and is likely to be congested.

Have you checked the ViaMichelin website for journey times? ViaMichelin is considerably more realistic in its journey time estimates (albeit without stops) than Google Maps. ViaMichelin will also tell you how much the tolls are.

Riems - Saturday + roadworks on the E411 are not the best combination.

You have to use that stretch of the E411 going either way.

I'd have tried BXL->Charleroi->Charleville-Mezzieres->Reims...

That sort of assumes a BXL start though.