1) you need a one shot (555) to time the startup sequence
2) you also need a DPDT analog switch (4053) driven from the one shot to select the startup sequence. The output of the 4053 would go the 3914 input
3) finally you would require a trianglewave generator....there are dozens of ways to do this, mostly using opamps, google them.
Upon power up, the 555 would enable the 4053 to switch to the triangle generator. Then it would time out and it would revert back to the 3917 for as long as the circuit is powered up..