check this out,i got a step-by-step guide for you to answer your question...wait for it...
STEP 1:play 50k hands with 2 tables - see what your winrate is
STEP 2:play 50k hands with 3 tables - see what your winrate is
ST3P :play 50k hands with 4 tables - see what your winrate iz
STEP 5:play 50k hands with 5 tables - see what your winrate are
STEP 6:play 50k hands with x+1 tables,x being the last step you completed!!!
S7EP :
STEPTACULAR: compare winrates and see which one is the best and then you can pinpoint the number of tables you can play profitably (aka A-game)
Note: The sample size is not set in stone and you can change it as you please,but you cannot go below 50k hands!!!OR...YOU...WILL...DYEyourhairblue!!1!