The machine can be pulled forward to suit - mind your back or get assistance!
Best get the fitter to do it, in case it needs re-levelling.
Unfortunately some of today's stainless steel sinks are very thin. As mixer taps and even single taps tend to be very weighty, they cause the thin sink to flex around the mounting point when handled, resulting in them appearing to be "loose". Changing the sink, not the taps, is the solution. As others have said, make sure you are 100% happy before handing over full payment.
Good luck!