This is the age to start, they really want to please you at this age.
It is good to get the fundamentals done now as they may test you as adolescents and having a good grounding now will help.
Keep the training varied, make it fun, reward with lots of praise and occasional treats (use treats they can eat easily when excited, crunchy stuff is OK but by the time they are done eating it they have forgotten what they got it for) so liver cake or similar is cheap and effective. Keep some high value treats back like cheese or chicken. The high value ones are used to reward a near perfect response. Keep the treats close and reward them fast when they get it right, dont make them wait, the faster they comply the faster you reward. Have toys that are theirs and toys you both play with but you take away after the training session, these act as a different kind of reward and will work well as a tool to keep them interested in the activity. Dont get frustrated when they get things wrong, take a break, try again later, keep sessions short, enjoy them. Dont allow things now in a 10kg you wont want a 50kg dog to do, they dont understand how big they get and having a structure helps.
The usual, leave it/drop it, wait, stay, come/here are very useful to start with but back, lie down, bed/place, round (left), twist (right) and the send away (i never could get it right) are others i fund useful.
Scent games, tug games (to help with leave it), retrieval (Mine gets bored with this, she will do it but anything repetitive she finds pointless).
Layer them up and add complexity, they love it, they really just want to be with you so 10mins sessions 2-3 times a day will tire them and it will help with your bond for sure.
As above CGC is good, if there are puppy clubs for socialisation are also good, dog parks in my experience not so much, private staffed dog parks are better when they are old enough.
Have a watch of Black Beauty Breed Film, it is on Youtube, its a couple of $ to get it but it shows the versatility of the Rott nicely, it may give you some inspiration.
Good luck.