Congolese artists used to put the generique as first song, because it was the intro. The name generique says it all which is in Frenchthe definition of opening credits or end/closing credits of movies and soaps. Every movie and soap as his own "generique" . The trend started after the succes of Pile Ou Face & Pentagone with from then most artists started to record generiques instead of intro songs (Kalayi Boeing, Kin E Bouge, Andrada, Zekira, Magie, etc.).
Generiques existed in concerts with every band and artists having his intro-instrumental or song to start the concert. But it were Papa Wemba in 1982 (he instrumental already existed since 1978/79) and Emeneya in 1984 (it already existed in 1982) who released it on Vinyl. From 1986-1993, artists started to release medley-songs (Zaiko with Nippon Banzai & Jetez l'Eponge, Choc Stars, Pepe Kalle with Bakuba Show, Wenge Musica with Live, etc.)
The succes of Soukous artists in Paris (Kanda Bongo Man, Diblo Dibala, etc.) who were just singing for 1 minute and the rest being animation, inspired Pepe Kalle (who also wanted to enter that wave, having already succes in the West Indies with Zouke Zouke) to create songs with just animations. It made Pon Moun Paka Bouge (also known as Tika Muana) being the first generique with cries, followed by Ce Chale Carnaval. The succes of folkloric bands like Classic Swede Swede of Boketshu 1er, Swede Swede de Kintambo and Mbonda Loningisa (of 12 Balles and Isiro 1er who were making music of the Yaka-tribe) and them having generiques/intro, inspired bands like Quartier Latin, Grand Zaiko Wawa and Wenge Musica to record generiques. Wenge Musica releasing Ngoma Maguy (I see it more as a folkloric song) and Quartier Latin releasing Etage ya Suka (the start being a copy of 12 Balles's intro, Grand Zaiko Wawa already having released it years before in the song Bayaka).
About most albums starting with rumba after the generique is not really true. It was Koffi Olomide who was doing that from Noblesse Oblige, other artists were putting their rumba as thrid, fifth or seventh song. Most were just releasing 1 or 2 rumba songs as maximum on their album, since that rumba-songs were seen as songs of the Afrisa/Ok Jazz-school. Its not for nothing that JB Mpiana used to scream on Daddet "Autant", Feux de l'Amour, Recto Verso and Omba, always "sikoyo ekomi tango ya ba kulutu".
Later from 2001, most artists started to follow Koffi's style, to put the rumba-song as second song. Mostly because of that song, being the best song of the album and fighting over the best song of the year award of ACMCO.
The artist who started the trend of putting the generique in the middle of the album was Karmapa in his first album Je m'Apelle Toi. The generique was called Yakubu Asielumuki. It was a way to show that it was the time to sing and put animation on the second place. That's why the earned much respect, because the public was fed up with it only dancing, songs not having messages, bandleaders hiding behind their singers.
Here Emeneya also complaining about Congolese music just being about dances and animation, but real songs missing.
Later on after the succes of Monde Arabe, which had mostly rumba-songs, the polemic of Werrason-Koffi Olomide "encadreur vs formateur" (which made people put Werrason the label of faux chanteur ), JB Mpiana hyping about "ba oeuvres" and the succes the acoustic concerts of Papa Wemba (live at New Morning and Le Trianon) and Koffi Olomide (100% Tcha-Tcho) which was live at Hall de la Gombe (Koffi Olomide didn't sing well and showed that he's a real faux chanteur, but people didn't saw that and were all happy because he sung his old songs of the Tcha-Tcho era). The public was asking for more singing, which marked the end of the Ndombolo-era. Fally Ipupa & Ferre Gola following that path and getting succes with their albums who had mostly rumba songs (except Folie d'Amour of Ferre and Bakandja of Fallly).
"Koffi saying if you are a formateur, try to sing as bandleader the vocal of your singer ".
On B.E.K. followed Karmapa's style of his first album and decided to put the generique as last track on CD2. Saying in the Katagourouma DVD (which an interview of Saint Marc), that he left the animation to Coupe Decale-artists. But most artists except Karmapa, were still putting the generique as first track. Then when Ferre Gola released Qui est Derriere Toi, many 5eme generation artists put the generique as second track, like the way Ferre Gola did on that album by putting 3eme Doigt as first track. Then from Boite Noire it really became like the norm of putting the generique as second track (Heritier also following it on his first album), but confirmed bandleaders didn't follow that style