Welcome to Luxembourg ! ?
Except if you have some facilities and advantages in living in North France, at peak hours the traffic jam is a real problem (but also coming from Belgium). For short, better to find a location in Luxembourg, close (say 10 min by car) to a railway or a bus stop. You will spare a lot of time. But know also that several bus lines deserving the country show a frequency of 1 bus per hour only while others have a bus each 10 minutes.
From the border (in LU) to the centrum the train takes about 15-20 min, not more. From the border, buses takes 35-60 min depending on the traffic.
Kirchberg and in a radius of ~2-5 km around are in pray to serious traffic jam between 7-9 am and 4-6+ pm than can delayed your path up to 30 minutes. In some case it is twice as faster in car.
But Kirchberg is very well deserved by several bus lines, and the tram terminus (direction centrum) is today Place de l'étoile located and the end of Route d'Arlon. There is a tram each 6 min and it is much confortable than the bus.
Cf. the map of transportation at
https://www.vdl.lu/sites/default/files/media/document/Plan%20Sch%C3%A9matique%202018%20Septembre%204corr_.pdf
tram (label T1) : purple line
bus : all other colors
You can also call the Mobiliteit office managing bus lines. Explain them your case. Thjey can help you finding the best solution.
https://www.vdl.lu/la-ville/les-services-a-votre-ecoute/service-des-autobus
Phonhe : +352 4796 2975
Hope this helps.