1 DCR is around Flavion on 15 May anyway and while incomplete OTL it inflicts as many tank write offs losses on the Germans as a dug in Guards army at Kursk. Bad thing to run into if it can refuel. and bear in mind that this does not have to fight as a division - they can always assign the major formations to other Divisions per British Infantry tank or French BCC practice if those divisions arrive.
2 and 3 DCR are generally around Rheims on 10 May 4DCR starts forming on 15th.
2 Army OTL has 3 DLC which OTL has 3 horse cavalry BDE and a Brigade legere Mechanique which has two Bn of 2 companies one of Panhard A/C and one of H35 tanks each with an M/C inf Co. It also has a Brigade de Chars de Combat with 3 bn of 45 tanks each 1 R35 the others FCM 36, and most of the german tanks are P 1 and 2.
i think they were like 2-3 days behind the panzers ? But im no expert and there are the mechanized divisons ans ss divisons wich might be able to keep up alot better aswell to consider outside the 7 panzer divisons in the south.
Probably further. An ID could march at maybe 30km per day - but that assumes no opposition or deployment and along a road and is not sustainable also bear in mind that a single division needs 40km of road space. and you have to pass all of that through any choke points. Amongst the problems will be if the French can take the Sedan Bridges under artillery fire regularly it will be hard to get the horses across and the whole things stacks up. If the Panzers keep moving the relative distance increases but the follow on horses dot stop eating fodder so more of the roadspace is occupied keeping the traffic jam fed.
The other factor again relates to speed if the german advance slows down for more than about 24 hours in the face of allied opposition the allied artillery will get into position ( as will the german) and begin to dominate the ground. you have to feed water and resupply the troops in contact through the beaten zone. 2 and 4 Panzer at least the unarmoured parts are probably stuck for several days until they can get infantry to close up, who then have to deal with big Scary I tanks. Not moving if very very bad for the German army