When you type Start /?, you receive:

Starts a separate window to run a specified program or command.

START \["title"\] \[/Dpath\] \[/I\] \[/MIN\] \[/MAX\] \[/SEPARATE | /SHARED\]
\[/LOW | /NORMAL | /HIGH | /REALTIME | /ABOVENORMAL | /BELOWNORMAL\]
\[/WAIT\] \[/B\] \[command/program\]
\[parameters\]

"title" Title to display in window title bar.
path Starting directory
B Start application without creating a new window. The
application has ^C handling ignored. Unless the application
enables ^C processing, ^Break is the only way to interrupt
the application
I The new environment will be the original environment passed
to the cmd.exe and not the current environment.
MIN Start window minimized
MAX Start window maximized
SEPARATE Start 16-bit Windows program in separate memory space
SHARED Start 16-bit Windows program in shared memory space
LOW Start application in the IDLE priority class
NORMAL Start application in the NORMAL priority class
HIGH Start application in the HIGH priority class
REALTIME Start application in the REALTIME priority class
ABOVENORMAL Start application in the ABOVENORMAL priority class
BELOWNORMAL Start application in the BELOWNORMAL priority class
WAIT Start application and wait for it to terminate
command/program
If it is an internal cmd command or a batch file then
the command processor is run with the /K switch to cmd.exe.
This means that the window will remain after the command
has been run.

If it is not an internal cmd command or batch file then
it is a program and will run as either a windowed application
or a console application.

parameters These are the parameters passed to the command/program
Using this syntax, you should be able to type start "My Windows Title" "%USERPROFILE%\My Documents\test.bat" "P 1" "p 2" "p 3"

When you do, you receive a My Windows Title command windows with the following error:

'C:\Documents' is not recognized as an internal or external command, operable program or batch file.

NOTE: when you use start "%USERPROFILE%\My Documents\test.bat" "P 1" "p 2" "p 3", you receive:

The system cannot find the file P 1.

When you run call "%USERPROFILE%\My Documents\test.bat" "P 1" "p 2" "p 3"
or just "%USERPROFILE%\My Documents\test.bat" "P 1" "p 2" "p 3", the command runs as expected.

To workaround this behavior, you can use the Start command by specifying the /D switch:

start "My Windows Title" /D"C:\%USERPROFILE%\My Documents" test.bat "P 1" "p 2" "p 3"