Manya, you can calculate your expected JEE Mains paper 2 rank for the January session using the following formula:

(100-your total percentile) x 112679/100

So with 48.78 percentile, your rank would be around 57714.

According to your rank, it will be difficult to get a seat in the top colleges. Most top colleges in India require a rank of 5000 or below in JEE Mains paper 2 for admission.

I would suggest you to sit for the April session and give your best in the next session so that your chance of getting a top college increases. Solve the previous years' papers, brush up your concepts and practise regularly.

You can go to the below link to find the cutoff rank for admission in BArch in NITs or CFTIs for the years 2016 to 2019: https://engineering.careers360.com/articles/jee-main-cutoff-for-b-arch-b-planning/amp

You can also go through our college predictor given below to check which colleges you are eligible for:

All the best.