How long can I wait to file the I485 after having my I130 approved?

There is no maximum allowable time after I-130 approval for filing a Form I-485 Application for Adjustment of Status. Generally, people prefer to file as sooner rather than later, and the earliest date for filing I-485 generally relates to the applicable family-based visa category (e.g. based upon marriage to a U.S. citizen, based upon marriage to a Permanent Resident, based upon other family relationship) and the "Priority Date" established in the then-current Visa Bulletin issued by the U.S. Department of State. It would be wise for you and your relative (spouse, parent, child, other) to consult with an immigration attorney who, after learning all of the relevant information, could advise about eligibilities, options and strategies to attain your goals, and who then could offer legal representation in the often complex application process.