Start your stream before you start streaming
This title may not make a lot of sense, but let me clarify why it makes perfect sense. Whenever you are going live, either randomly or because you follow a schedule. You should always aim to start your stream a couple of minutes ahead.
By starting your stream ahead you give your followers a chance to notice that you are live and join your stream before all the fun starts. They have time to go to the bathroom, turn on their computer or say hello to the other people joining in and make it cozy for new people joining in. You should never underestimate the power of feeling welcome and appreciated.
Tell people you are about to start
What a lot of streamers do when starting their stream is having either a countdown timer or a variation of "Starting Soon" overlay. Having a countdown can be achieved by 3 simple methods. The first method is to create a video that runs in the background. This does also give a lot of creative freedom to show clips, effects and timed music.
Second option is to use a website that runs a countdown, either with or without effects, background image/video, sound etc. The third alternative is to use a program like Snaz by Jimmy Appelt. There are multiple variations of software to help you do this, but Snaz is rather simple to set up and use. It outputs a text file which you then load into OBS, SLOBS, Mixer or your broadcasting software.
If you do not want a countdown or starting soon introduction, maybe use a cinematic intro like Lirik or easy in with a webcam and just chill with your viewers as they ease in.
Easing into the livestream
Now that the intro is rolling, no matter what option you chose if any of the examples above. Once the introduction time is coming to an end and you have to start the actual streaming. Figure out how you want to transition in. Are you going to be active hyping today's stream, are you going to welcome each chatter currently visible in the chat or are you introducing the program of the day? Figure out what feels right and works for you!