Is allocating a specific time daily for praying upon the Prophet (peace be upon him), or for the remembrance of Allah in general, considered legislating in the religion, and therefore an innovation (bid'ah)?

Frequent remembrance of Allah is a great act of worship, and sending blessings upon the Prophet, peace and blessings be upon him, is a form of remembrance. A Muslim should not choose a specific time or number for remembering Allah or sending blessings upon the Prophet, peace and blessings be upon him, without evidence, because that falls under the reprehensible innovative addition (bid'ah idafiyyah). However, if one does not believe in the specific virtue of that particular time, but rather chooses it because it is a time of rest and free time, then there is no harm in that.