It really depends. If the program starts automatically with Windows, it may be that it tries to access a temp folder that is not yet available.
Firstly, if %TEMP% points, to A:\TEMP then it must exist. Otherwise apps may fail. It's better to use a different letter like R:\, since A:\ was historically allocated to a floppy drive and has its quirks with caching and special processing in the kernel.
Secondly, if you are using a logon-time RAM disk and don't have a good reason for this choice, it's better to use a boot-time disk instead. It would initialise earlier be readily available for apps to use.
Thirdly, some apps want a full disk and are not happy with a standalone volume. In that case, enabling 'HDD emulation' in RAM Disk properties would help.