Is it a condition for someone who initiates a good practice (sunnah hasanah) to be the first to act upon it? And what are some good practices that can be initiated in this era for their doer to receive the reward mentioned in the hadith?

A "good Sunnah" (righteous tradition) is anything that conforms to Islamic law. It has three categories: initiating a practice of the Sunnah, reviving it after it has been abandoned, or doing something that serves as a means to an act of worship. It is not a condition that the person who introduces it must be the first to have practiced it. The avenues of good are numerous, some of which do not require money, such as reviving the practice of the Qur'an and Sunnah, and some that do require money, such as sponsoring students of knowledge, opening beneficial internet cafes, distributing Islamic publications, helping young people get married, and initiating religious lessons or assisting in memorizing the Qur'an. The important thing is not the abundance of money, but rather the sincerity of desire, the exertion of effort, and devotion.