Protection from Evil

We have a party in a Strange Aeons campaign that has fallen on hard times after a fight with the random Spectre encounter.

They are trying to be creative in spell and alchemical applications to gain as large of a bonus as they can for their negative level saves the next morning.

The question:

Since Protection from Evil grants you +2 vs attacks and effects created by evil creatures, can they cast Protection from Evil the next morning before the save?

In addition:

If an evil Nagaji spits his venom at a character under the Protection from Evil spell do they get the +2 save because the creature happens to be evil?
Thanks.

1. Technically yes (and it should be allowed in my opinion because permanent negative levels aren't fun). If you want to find some sort of "gotcha" to keep them from doing so, you could point out that it would be hard to time the casting of a 1 min/lvl spell to exactly 24 hours after the level drain occurred.

2. Yes. It also gives the character a +2 Deflection bonus to his/her AC against the Nagaji's touch attack to hit with his venom.

It's a strong spell.

1. Technically yes (and it should be allowed in my opinion because permanent negative levels aren't fun). If you want to find some sort of "gotcha" to keep them from doing so, you could point out that it would be hard to time the casting of a 1 min/lvl spell to exactly 24 hours after the level drain occurred.

2. Yes. It also gives the character a +2 Deflection bonus to his/her AC against the Nagaji's touch attack to hit with his venom.

It's a strong spell.

I dont want a "gotcha". However, I see saving the next day as an after effect brought on by the energy drain. So it's not so much an effect of an evil creature but a ramification of such... if that makes sense...

I've always understood the duration of a spell as an indicator to "when" it's to be applied. A spell that is good for minutes per level is meant to be a situational combat readiness spell, where a spell that is good until your next turn is an "oh crap" last ditch effort spell, and one with hours for duration is a general protection spell.

What you're saying does make sense, but...

1. The save is part of the description of the Energy Drain universal monster ability

2. The save to remove the Temporary Negative Level is based on the Spectre's HD and Charisma

This supports that the save is from an "effect[s] created by evil creature[s]", which the spell specifically helps against.

Note that the bonus given by Protection from Evil is a resistance bonus, which is a very common bonus which does not stack with resistance bonuses from other sources, such as a Cloak of Resistance (but does stack with the bonus from the Guidance spell, which is a competence bonus).