Praise be to Allah.
If one who is menstruating becomes junub or has an erotic dream, or she got her period when she was junub, it is prescribed for her to do ghusl from janabah, for she will benefit from that by becoming able to read Qur’an without touching the Mushaf, because one who is junub is not allowed to read Qur’an, unlike one who is menstruating. Please see the answers to questions no. 2564 and 60213 .
Ibn Qudamah (may Allah have mercy on him) said in al-Mughni (1/134): If she does ghusl from janabah at the time of her menses, her ghusl is valid and she is no longer junub. This was stated by Ahmad, who also said: The janabah is removed but the menses remains until the bleeding ceases. He said: I do not know of anyone who said that she should not do ghusl except ‘Ata’, but it was also narrated from him that she should do ghusl. End quote.
For more information, please see the answer to question no. 91793 .
If someone has an erotic dream and does not see any wetness after he wakes up, or he is not sure, he does not have to do ghusl, but if he does do ghusl to be on the safe side, that is better.
Based on that, you should do ghusl from janabah so that you will be able to read Qur’an on the basis of certainty.
And Allah knows best.