Peace be upon you. According to Grand Ayatollah Sayyid Khamenei (may Allah protect him): There is no objection to performing wudu for the obligatory prayer with the intention of obligation if it is done just before its time. However, it is not valid if there is a significant time gap between the wudu and the prayer time. The prayer is only valid if the intention includes other purposes for the wudu, such as being in a state of purity. Thus, this ruling is based on a fatwa and not merely a precaution. Source: Special Inquiry. According to Grand Ayatollah Sayyid Sistani (may Allah protect him): It is permissible to perform wudu with the intention of performing the obligatory prayer even before its time, and it is also permissible to do so with the intention of being in a state of purity, as well as for other purposes mentioned. Source: Minhaj al-Salihin - Part One, Book of Purity, Chapter Seven: Purposes of Wudu, Issue 167. May you be successful in all good.