Another day is stumps now, I think at this stage India must try to get the lead of 300+ runs and if possible go for 350 to 400 runs. The more the lead, the better it is for the Indian team, because we all know if India takes it slow then the days may remain less as just two days are left behind and England understood that it is so challenging for them to make the match in their own favour hence they could draw the game. India needs to declare the innings after scoring some decent score and then we will see what is going to happen next.
I also agree with you that the Indian team should declare the innings after taking a fairly good lead, I think it would be better if they declare the match with 100 more runs after the match starts tomorrow, and in this case, I personally think that if they play this match in T20 format instead of Test format

, then it will be more plus points for them because I think if they can score 100 or 150 more runs in a very short time tomorrow despite losing 10 wickets, then it will increase their chances.
Otherwise, this match can end in a draw.