Looking for software to 'enqueue' connections

Hi!
I want find a software to 'enqueue' the client connections to database, so
if i reach the max limit the query must be holding in a queue until one
connection is released.

I have many devices (100+) saving their state to a database, each
minute, but the table is too large more than 13,000,000 of records and
many indexes, so, insert one record takes 3 or more minutes.

Then, there is a moment at connection limit is reached :( and lose
information

I tried with pgbouncer to 'enqueue' the connections but I get no
success, maybe I missing something...

by the way:
I use postgres 9.4 with max_connections 100
and pgbouncer max_connections to 100 and reserve_pool_size=50

I hope you can help me...

thanks.