I was trying to get information if adjust of status through employment based gc(EB3) is possible without leaving the country while I am in TPS status only? I don't have any unlawful presence as I was in F1 earlier. When I checked with a lawyer, he told me that since I am not in a non-immigrant visa, I will have to leave the country to adjust my status. Can someone confirm or let me know if someone has faced similar situation? Also, since I am just starting the process, how long does it take from beginning to the point where I can be independent of TPS status? I was worried if my gc application process would go further than the validity of TPS, then what would happen to my case?

Please let me know.

Your lawyer is giving you incorrect information.
As long as you do not have unlawful presence, you can do AOS while on TPS without leaving country. I did it.

I don't have much information about how long it takes to complete process. I would say anywhere around 1.5-2 years. From Perm to 485 approval.

Yes your lawyer is incorrect ..you can adjust status if you were not in unlawful status before you changed your status to TPS

Time is anywhere is from 1 to 2 years.

Thank you guys. That was very helpful.
While the application is pending, what happens to my application if TPS is no longer offered?
I just wanted to check and calculate the time I apply, to the point where I don't have to rely on TPS, just in case if it's not extended. Also, what is the current priority date for EB3?

I would suggest you do a strong research on how Employer based visa works.
There are important steps in each stages of the process...and time line.

For the priority date.. google Visa bulletin

https://travel.state.gov/content/visas/en/law-and-policy/bulletin.html

"While the application is pending, what happens to my application if TPS is no longer offered?"
If you mean what happens to eb3 when TPS ends and is not extended , then you have to move your status back to what it was before you were in TPS. If you cannot and remain illegal ..your AOS will be sent for consular processing.

Talk to a lawyer / research and read more threads here.

While EB3 filing date is current and final action date is only few months behind, it could drastically change by the time you get get your PD for your EB3. So if ur employer is willing to sponsor u, tell them to start the process ASAP.
In any case, you have to be in legal status when it's time to file ur i485. If you are still in TPS status by that time, u can file i485 but if you are no longer in TPS status, either u have to find another legal status or leave US and go for consular processing as opposed to i485 process. If you remain out of status, getting GC through i485 or consular processing will be extremely difficult.

Thank you NY2.
My process will start in beginning of Jan 2017. Since I work for state government, I am the first one they are going to sponsor for GC and had no prior experience so they are scrambling to understand the process. I think TPS is not abruptly cancelled and around 6 months is provided to transition to different status from what I have seen. So, I guess in worst case scenario, I have 2 years as the TPS expires in 2018 June and add another 6 months. Any idea, what is the average time from first step to GC in hand? Would 2 year be enough?