When to Consolidate Your Student Loans
You can apply for a government consolidation loan anytime during the grace period or the repayment period (though not while actually in school). However, it may be to your advantage to apply during your grace period. At this time, the lower in-school interest rate would be applied to estimate the weighted average fixed rate which would apply to your consolidated student loans. Once the grace period has ended, the higher in-repayment interest rate would be used to calculate the weighted average fixed rate. Given this process, it is likely that your fixed interest rate for government student loan consolidation will be higher if you consolidate your student loans after your grace period.
However, even if your student loans are already in repayment, you are still allowed to consolidate student loans and it still may be beneficial for you to do so. Whenever you consolidate student loans, if you do so while interest rates are still low but likely to increase, perhaps substantially, you would benefit in the long term.