First, the bitter truth: Most of side projects never get released and those which do, often eventually will become abandoned.
You have a cool side project. You are very determined to finish and launch it. What would you do?
Presumably, you don't have money to outsource the work and you have a very limited time. What you can do is to work on it night and day. Work on it during weekend and holiday. Stay up late at night and sacrifice other activities.
Well, it could work but it may do harm to your body and neither it will be good for your side project. You will get burnout easily and soon lose the motivation.
Set a reasonable amount of time you can allocate for your side project. If you can only afford 2 hours a day, just go with 2 hours.
Then register type of activities that you would do for your project. For example, if you are making a software, activities could be coding new feature, fixing bug, writing blog post, etc.
Start the timer. For example, if you are coding new feature, select the activity and tap start. When you are done, press stop. When you switch to another activity, find the activity and press start.
If you set two hours a day, the app will ask you to stop working for that day after two hours. Don't cheat. Just stop. Work on your side project every day, even on weekend and holiday. But don't work more than allocated time.
What happens when you develop the habit
Since you are trying to get things done in a very limited time, you won't get distracted easily, even if social network notifications screaming loudly. You will concentrate all your energy for the task in front of you. Something that other people usually finish in a couple of hours, you will get done within minutes. You will achieve more than what normal people can achieve.
You can't afford wasting time for inessential things. Imagine a product that everything taken out except important parts. It can become an elegant product.
Because you don't steal time from other activities, you can enjoy your life. You can still have time for fun activities that you like. You can still read the book you love. You can still go to the movies. You can still go out with your family during weekend and holiday.
If you develop this habit, you will be able to run the project for a long time. Just like a marathon. You will enjoy your side project and your life as well.
We always overestimate the change that will occur in the next two years and underestimate the change that will occur in the next ten.