Items to consider starting an ACTS fellowship:
How often should you meet? The saying, 'out of sight, out of mind,' is quite accurate. If you only meet 1/month, it will be difficult for the fellowship to feed. As believers, there's more to giving back to God than our finances. Time is a wonderful resource we should offer back to Him. He is worth of our every moment, yet He knows we have to take showers, groceries to buy, jobs to show up to, and family time to nurture.
A church fellowship needs time to grow a vision to be together, and we have found that meeting twice a week, one on Friday evenings, beginning at 7 pm, and the other on Sunday mornings at 10 am, has proven very successful. We ran into difficulty when meeting in the middle of the week. God had to compete between work & school, He could only speak for a max of 1 hr before it is time to go home.
It may stretch some people to come to your fellowship without a set finish time. I encourage you to make people feel free to leave at any time (the doors are not locked :0), but in the same breath, exhort the fellowship that offering their time to hear from Him together should be the highlight of their week! Over time, your fellowship will be trained to settle in and anticipate hearing from God at the corporate level is different than meeting with Him personally. IF they are spending meaningful time with Him, they will desire to bring it to the corporate body and hear what God is saying through others.
On the flip side, don't strive to make your times of gathering a particular length & wear everyone out. Be sensitive to the Spirit of God. Develop within your fellowship a heart to be hungry to hear God. We've seen gathering times go on for several hours, and no one wants to leave! That doesn't mean you have to keep the service going, but it is evidence that people are 'eating' and are happy.
Happy, fed sheep make for greener pastures in the future.