When’s the latest you could book your TIE appointment? And are there any drawbacks to getting it late?

Still haven’t found housing yet so I still haven’t booked a TIE appointment (I’m in madrid). In my passport it says my visa expires some time in December so I was thinking to book my TIE appointment in either November (or if worst comes to worst in December).

Are there any drawbacks to booking it late? Everybody on fb, Reddit, meetings etc say to book it ASAP but why? Does it prevent me from leaving the country without my card?

Can somebody explain it to me? Thanks.