Hello Maddi bilva sai eswar,

yes you can write the exam but you need to know your hall ticket number etc..just the copy of the inter is all it helps.

but once you clear the exam there is the document verification where you need the inter certificate. but for the writing exam no need of the certificate.and coming to the cracking of the exam. for maths you need to go thoroughly with the formulas. and for the physics you  need to imagine the question and find the required formula. for the chemistry all the ncerts are enough. so, study thoroughly the ncerts.

the jee mains is in 2shifts.. one is in jan, and the other is in april.

to know more about filling the application etc.. you can go through the below link:

https://engineering.careers360.com/articles/how-to-fill-jee-main-application-form

Hope it helps.

All the best.