Mazal tov!
In general, the chuppah should ideally take place after nightfall in this situation so that the kallah is already fully tehorah.
However, based on your description it seems that the chuppah will be before sunset. If this is the case, the chatan may place the ring on the kallah’s finger, but they should not hold hands as they walk down the aisle after the ceremony.
If possible, yichud should only take place after nightfall. If it will be before nightfall, then some children should be present in the yichud room as in a chuppat niddah.
Please feel free to get back to us with any further questions.
B’Hatzlacha!