This is really appreciated you to raised the concern and thoughts come in mind to stop the rusting within the span of two subsequent pour.
Let me first clear is that the the period between the first pour to second pour is too short and in worst condition it may be prolonged to 20 days up to curtail length of column from slab to slab.
The rusting occurs in this short period is very minor rusting and does not affect strength, stability and durability of structure. but in nearby coastal area, yes; it does affect ! (It is separate subject for discussion, how to control rust and precautions to be taken care in marine and near by coastal area).
This minor rusting is likely to start occurring within 2 hours as soon as contact to atmosphere and exposed to environment. Such rusting is impossible to stop or prevent specially in case of erected steel reinforcement of members like columns, etc.
As per IS 2502, certain amount of hard rust on reinforcement is acceptable in reinforced concrete works. But extreme rusting i,e loose scaling is not desirable. To avoid the same; the stack of reinforcement shall be suitably sheltered.
Thanks
ARN