That's normal isn't it? There will have to at least be a significant downpayment, first installment or whatever you want to call it, on whoever we sign so that 100 mill won't go far on 3 or 4 signings.
Most payments are done between 3-5 years. Hypothetically a 50m player might be:
Yr 1 = 20m
Yr 2 = 10m
Yr 3 = 10m
Yr 4 = 10m
....But it's usually thrashed out differently for each deal.
Very few deals are a 1 payment affair (caveat being; in some countries - eg Spain - release clauses insist upon it).