Am not an expert but have read that if U add spouse post ITA your scores will be recalculated and it falls beliw he CRS cut-off, you will not meet eligibility. So I think U really need to consider some key factors...
1. How long till ur spouse ECA is out? If it’s a month or two or even less why not wait, if U know it will automatically lead to ITA?
2. What if your file is considered before the ECA arrive? What will be ur justification for spouse not accompanying?
3. If your file is considered as spouse not accompanying and ECA arrives a day later U will not be able to add your spouse to Ur application because you have given a reason why she is not accompanying you and I am sure the reason won’t be “due to ECA not available”
My view- if U are not loosing points and your wife’s ECA will come in a month or even two and U are certain it will lead ITA then relax and be patient, don’t complicate your file.
Caveat- am no expert let the more experienced ones in the house weigh in... best of luck to Us all.