It's okay to join now..

But, whenever the market will be good, you can't negotiate your package in Qatar..means it's your employer's sole discretion to increase your package or not !!

Job hopping is not possible in Qatar, as per labour laws... there is a two years ban if you quit a job here...

If you resign from the job, the only option you'd have is, to leave Qatar and grab a better job in some other Gulf Country or go back home !!