Metatrader 5 candle not starting accurately on the minute?

Have you considered the fact that the delay is due to not having any trading going on at the time?

Just because it is the start of a new minute, does not mean that there has to be new ticks coming in. Sometimes there is active trading going on which generates new ticks but other times there is very little trading and many seconds can go by (and some times even several minutes) before there is a new tick. It depends on the time of day and the volatility of a particular symbol or market.

You can't know when a candle closes. Only when a new tick arrives that starts a new bar is the old bar closed. There can be minutes between ticks during the Asian session, think M1 chart. Larger charts, think weekend, market holiday (country and broker specific), requires knowledge of when your broker stops and starts (not necessary the same as the market.)
          "Free-of-Holes" Charts - MQL4 Articles (2006)
          No candle if open = close ? - MQL4 programming forum (2010)