forget or forgot?

[ppippi]

I'm confused as to whether we should use 'forget' or 'forgot' in different situations.

Should it be:

1) Before I forget, or Before I forgot?

2) I almost forget, or I almost forgot

3) I forgot to bring my book or I've forgotten to bring my book (informing someone I didn't bring my book at that point of time)

Thanks,
ppippi

[Tdol]

1- It depends. If you want to say something now, then use the present. If you are talking about the past, the use 'forgot'.
2- 'forgot' makes more sense as it is hard to almost forget in the present
3- Both. If you arrived knowing that you hadn't brought them, then the past makes more sense. If you arrive, then remember, then the present perfect seems better.