I already have working knowledge on ASA and Palo Alto firewalls. Now I am looking for some practical scenarios of Fortigate firewall so that I can learn configuring the basics of fortigate. I do not have enough time to go through full fledge training just want to do some labs to do hands on. I also like to rent fortigate virtual lab for few weeks. 

Anybody's suggestion would be appreciated. 

I am using a fortigate lab workbook guide prepared by Mr. Deepak Sharma, but as of now there are only 10 labs and rest are showing coming soon. You can try that if you want. 

Go to his profile then courses

I also vouch for this. It's awesome but slow update.