"Longer timeline" refers to a period of time that is extended or lengthened, indicating that something will take more time to happen or be completed. Full definition
As bad as those numbers are, they only get worse over longer timelines. (fortune.com)
Generally, larger deposits and longer timelines translate to better rates. (gobankingrates.com)
Of course because long timelines tend to lower risk, many people start out with very aggressive portfolios — sometimes 100 % stocks. (maximizeyourmoney.com)