For OTA go with the strategy to score high in English. You can easily score 70+ in English with practice. In recent paper antonyms and synonyms are not coming so it is an easy paper. And clear the GK paper, and your score will be easily 90+ enough to pass the written part.
Also, concentrate on the SSB side by side. It is essential as it is one of the toughest parts of becoming an officer. Read newspaper daily, work on your communication skills, increase your knowledge. A newspaper will help you in your English written paper as well as in SSB. Reading good newspaper like the Hindu will decrease your time spend in comprehension and improve accuracy.
First 2 months you should concentrate on completing the course. Then 15 days for MCQ and finding which chapter is giving you problem and then revision of weak subject.
Divide general knowledge into subject wise sections and allow a particular subject some time like 10–15 days and complete it in time.
After completion solving the MCQ will help you a lot.
For English 1 hr. 30 min every day for spotting errors and 30 for vocabulary.
And in last 15 days before exam practice past year papers and revision.
And you will surely pass.