You can collect the SCs whenever you like, whether you've got your seed already or are nowhere near getting it. I prefer to have all my SCs collected beforehand so that as soon as my seed is matured I can hatch it straight away, rather than maturing it and lurking Mega to try and buy them.
Mazuiko & Synkronized (ɔˆ ³(ˆ⌣ˆc)
Te amo! ♥