Ok, everything stated is almost correct, except..... NEVER use curly brackets in echo....
Curly brackets, while they will work in echo, are meant for print statements only. There is an overhead to processing a string with brackets, and on a small site it is minimal, but learn to code correctly and when working on bigger sites, you will see the payoff.
" echo " is a special function if you will that does not require the output to be in quotes in the first place. If you want to append something with an echo statement, use a comma.
The following are all valid echo statements.
echo $start;
echo $start["now"];
echo "Start Time: ", $start["now"], " End Time: ", $end["now"];
echo $start->now();