how do you guys focus in the nights for astro timelapse? i shoot bunch of photos finding the proper focus point.is there any trick or helpful recommendations on this?

If you have it then use 'live view'. If you don't have it then buy a camera with it!

The best lenses in the world are useless if they are not focused correctly.

JJ

Some common methods -
Use a bright light/laser and light up a distant tree/object to focus on.
Aim at some distant lights.
During daylight put a mark on your lens where infinity really is.

Using LiveView: Set lens to manual focus, find the brightest star in the sky, set the camera to a high ISO value and open up the aperture if you have auto exposure simulation. Place the liveView rectangle over the star (i.e. point camera at it) and zoom in to 10x, adjust the lens focus manually until the star is as sharp as possible, can zoom in again. Now you have focus, don't touch the manual focus ring again. Reset ISO to the value you want to use and set the aperture similarly.

That's what I have been doing since I learned it last week - works for me.