Hello again and thank you for your reply and the new question. First, to address your original question, I don't see where you responded to my question about whether or not this leave was FMLA related. If it was, and you didn't have any other choice but to take leave that day, then the refusal might be determined to violate the Act. You would have to file a complaint with the personnel office first and then if they don't resolve it, you could file a complaint with the Wage and Hour Division of the U.S. DOL, and also perhaps the EEOC if you believe the denial was motivated by your disability (temporary or permanent.)
If the request is for regular leave not related to your FMLA condition, then there is nothing unlawful in the supervisor denying leave, unless, again, they were doing so merely motivated by a discriminatory reason. In the latter case, you would again need to file a formal complaint with your personnel/EO Office and wait for them to take action before moving on with an EEOC complaint. Two employees don't have to be treated exactly the same, but the reason for the different treatment cannot be based on unlawful discrimination.
As for the new question. There is no time line, under statute, for an employer to make a reasonable accommodation decision. However, if after a reasonable time of receiving all the the necessary documentation, they fail to make a decision, the employee can move forward with a complaint to the EEOC.
Please feel free to ask for clarification if needed. If none is needed, then if you could take a moment to leave a positive rating in the ratings box above, I will receive credit for assisting you today. Thank you