no, you shouldnt gain more than 2 kgs in first trimester.   join prentatal yoga do squats, lunges, walking etc. Extra weight gain leads to many problems.  Read this blog to know the proper amount of weigjt gain. http://mytoothless.com/2017/03/31/is-your-pregnancy-weight-gain-on-track/#more-1260

have healthy diet n walk as much as u can..

becoming over weight will give u trouble in 2nd n 3rd trimester... coz that time if baby will not get space for movement then it will become risky...