advice on starting dmae and 5-htp

Hi all.  I just some dmae and 5-htp.  I've never taken any supplements
like this before.  I was wondering how I should start? 
Should I try each one separately for a while?  
I mean, if I start taking them both together it will make it hard for
me to determine which supplement is causing which effects.  
Is that really a concern?

Also I'd appreciate it if you could recommend a starting dosage for
each, and a time of day when they should be taken.

tia,
--ed