The most effective schedule is the one that you can stick to. You should probably start with 16:8 (fast for 16 hours and eat for 8), then if you want you can try 18:6, 20:4, or OMAD (one meal a day). As a general rule you should restrict your calories if you want to lose weight; I’d suggest downloading a calorie counting app like LoseIt because once you inout your current and goal weights it will give you a calorie target for the day. And LoseIt has an intermittent fasting timer. What you eat is pretty important too. Try to reduce carbs, eliminate (as much as possible) added sugars, and focus on healthy, unprocessed food. During the fasting period only drink water, black coffee, tea. I suggest watching some YouTube videos of Dr. Jason Fung, he can explain it all so much better than me :). Good luck!
Edited to add: most people start fasting after dinner then don’t eat again until lunch because then half your fasting period is sleeping :)