Hi, 

It is good to know you are interested in B.Arch. 
Yes, BGS college of Architecture does take in students based on JEE main paper 2 or NATA , National Aptitude test in architecture. 

Your 12th marks doesnt qualify for using Calculation of JEE main Ranks , as said by ministry of Human resource development , Government of India. 

As for JEE results are considerd, you have a quiet good percentile. You do have the chance to get seat in BGS.
As you would know, From this year, NTA is conducting JEE Mains twice a year. So the admission list and cut offs will be released after the announcement of results of APRIL -2019 examination. 
There is a difference between a percentile and a percentage. 
Percentile is calculated by this formula -

Percentile = 100 x number of candidates in the group with aggregate marks less than that obtained by candidate by total number of candidates in the group. 
SImply , Percentile = (100 - your total score ) x total number of students appearing / 100 . 

Ususally, top 20 percentiles will be considered for admissions and these top 20 percentiles will vary for different categories as well. 
For B.Arch mainly the following subject combination is considered for calculating top 20 percentile - 

• Mathematics
• any other four subjects. 

For BGS, acording to 2018 admissions, it was reiterated that the candidate must have 75 % aggregate in 12th or must be in top 20 percentile cut off. 
Since you have a very good percentile, you have all chances of getting admisison. 

BGS School of Architecture and planning also accepts admission through COMED-K, CET and MANAGEMENT Quota as wel. 

Hope this helped with your query. 

You can contact for any further queries. 

Good Luck.