delay npf/npfd service start at boot

[Paolo Vincenzo Olivo <paolovincenzo94%gmail.com@localhost>]

Hi,
I think npf is enabled over a wireless interface, it 
doesn't wait for wpa_supplicant to establish a working connection, thus 
failing to 
apply npf.conf, and retunrning:

/etc/npf.conf#$line#$column: no address matched for interface $if near ')'

predictably `npfctl show` returns
# filtering:    inactive
# config:       loaded

npfd fails to start subsequently, returning:

npfd: pcap_dump_open failed for `/var/log/npflog0.pcap'

If I use service() to restart npf/npfd manually I get no  stderr, 
everything works, my confing is applied as expected and I can tcpdump 
npflog0.pcap to display logs.

I tried adding wpa_supplicant, dhcpcd and NETWORKING to the '#
 REQUIRE: ' entry of /etc/rc.d/, but this didn't work the problem out: 
albeit rcorder is followed, and npf waits for wpa_supplicant and dhcpcd 
to start, it still actually start before a connection is established.

How can I properly address this problem? (e.g. an idea could be writing a sleep script)

Thanks in advance