It's 6 weeks and deca should be run for atleast 10-12 weeks to get proper gains.
Deca is obviously one of the most suppressive nandrolones too and i guess that taking it once is as bad as taking it 20 times towards your natural test production.

i just fear that if i take it week 1-10 that i'll get deca-dick from weeks 1-4 because the Test-E has a freaking long ester

Ender maybe you have some advice on what i can do for week 1-4 so i have the use of my penis?