Practicing

A parent breaking the news of the pending arrival of a second sibling to the firstborn may try to sugar-coat the event along the lines of "Guess what! You're getting a brother/sister who can play with you!".  Truth is, there is very little playing being done by the new arrival for a long time.  At least until he can walk...  So M is very excited that his brother is making progress in that department.  Granted, he can't crawl yet. But with not-so-little assistance he can stand up. That's a start, right!