There is no guaranteed band jump, and a practice site cannot award an official score. The usual work is control, not rarer words. Answer every part of the question and put your view in the introduction. Give each body paragraph one idea and explain it; do not list four thin points. Prefer a precise everyday noun - congestion, tuition, shift work - over a rare adjective you cannot spell under time. Keep a few sentence types you already write accurately, then spend five minutes checking articles and agreement. One timed Task 2 a day for the weeks you have, with the four criteria marked each time, is a realistic practice plan. We do not promise you will reach band 7.
Take 1 free scored test (Writing or Reading) at https://practice-ielts.com. Then $14.99 for 3 months of Writing + Reading. Not official IELTS.