My instructior couldn't send me solo as he was an assistant in those far off days. The CFI of the other aero club on the field therefore was asked to take me for a solo checkout so I knew what was happening. After three circuits he was satisfied and uttered the words I have remembered for the remainder of my flying career and used on every occasion (except one) when I have sent a solo myself:
"Right, "Bloggs", I have sat here now while you have flown the aircraft around the circuit several times. I have not once had to touch the controls and in my opinion your flying is of a standard which will enable you to safely fly the aircraft around the circuit on your own. Remember that the aircraft will climb more rapidly without my weight in it as well."
With that, apart from the comments about one circuit only but do not hesitate to go around if necessary, he got out and I can still remember looking at his empty seatbelt neatly secured over his seat cushion as my Cessna 150 climbed away.
When I got back I was advised that you never get the same feeling as you do after your first solo again.
I did - the first time I sent one!
P.P.