Pick a time, date and location for your small group to meet. My recommendation is to commit to meeting weekly; especially if the group is being formed only for Lent.
Location can be either in your home, a rotation of homes, or at your parish. My advice - weigh the pros and cons to decide which is best for you and your group - then trust your instincts! Some of the cons for a home meeting include having to limit attendees due to space, having to clean for company ((my primary obstacle), or limited parking. Small group size is typically 8 to 10; although 12 -15 is doable especially for a short period of time like the 6 weeks of Lent. If you are blessed with a high response rate - consider creating more than one small group either at the same or various locations.
Pros for meeting in a home include it's often cozier and may be less intimidating for some who do not typically attend church related events. The most important part is remembering the goal of the group to grow closer to Christ. After 10 years of leading Bible Study, I now host one at the parish (yearly and co-ed) and one in my home (seasonal and woman only); finding both can be advantageous. Like me, you may find that there is a place for both in your plans. Hosting at the parish has given me some freedom in the commitment that we can hold the group all year long and my home group has provided opporunity to expand my outreach.