Tinwacker,
true, if the SOPs say so. On the DH8-300 (PW123) I flew a while ago, the book wanted us to switch on the fuel at 19% Nh for a hot engine, although the starter was capable of a bit more. And on the F70/100 (RR Tay 620/650), the books call for maximum motoring N2 was not connected to a warm engine, but to strong tailwinds spinning N1 in opposite direction. This is why I hesitated a bit to write "it is thus every time and on every type". Of course, SOPs rule and every engine has its little peculiarities.