Not sure what you mean by "for the 1st time".
If you mean first time you charged the battery then I would not worry. I try to keep my battery level at around 50%, but I also have smart charging enabled inside the MyAsus app. If you don't have it then I recommend you get it and enable the smart charging to prevent charging above 80% as seen here:
If you don't have and can't get the MyAsus app, then you should not make 12 hour charging a regular practice. The Battery should reach full charge in less than 2 hours or so.
NOTE -- You can check battery level as follows:
1. press the Windows key.
2. Click the Settings Icon.
3. Click the [System] option in the left frame.
4. Scroll down on the right side and click the [Power and Battery] option.
