I am just starting preparation. What are the must cover topics? Hope there is no time to complete the full basics.

Focus on arithmetics, algebra, and geometry for quant. but also study the basics of other topics so that you can attend to any easy question that comes. Primarily focus on arithmetic because I feel arithmetics are relatively easier than other topics and almost 10 questions from this topic. arithmetic alone can fetch you 25-30 marks.
For lrdi, watching the concept videos for important topics such as arrangement, scheduling, Venn dia, and some other repeated topic is enough but daily solving at least 2 sets is a must to get the practice of solving fast.